media/blink/key_system_config_selector.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "key_system_config_selector.h"
   6
   7 #include "base/bind.h"
   8 #include "base/logging.h"
   9 #include "base/strings/string_util.h"
  10 #include "base/strings/utf_string_conversions.h"
  11 #include "media/base/cdm_config.h"
  12 #include "media/base/key_systems.h"
  13 #include "media/base/media_permission.h"
  14 #include "media/base/mime_util.h"
  15 #include "media/blink/webmediaplayer_util.h"
  16 #include "third_party/WebKit/public/platform/WebMediaKeySystemConfiguration.h"
  17 #include "third_party/WebKit/public/platform/WebSecurityOrigin.h"
  18 #include "third_party/WebKit/public/platform/WebString.h"
  19 #include "third_party/WebKit/public/platform/WebVector.h"
  20 #include "url/gurl.h"
  21
  22 namespace media {
  23
  24 using EmeFeatureRequirement =
  25     blink::WebMediaKeySystemConfiguration::Requirement;
  26
  27 namespace {
  28
  29 static EmeConfigRule GetSessionTypeConfigRule(EmeSessionTypeSupport support) {
  30   switch (support) {
  31     case EmeSessionTypeSupport::INVALID:
  32       NOTREACHED();
  33       return EmeConfigRule::NOT_SUPPORTED;
  34     case EmeSessionTypeSupport::NOT_SUPPORTED:
  35       return EmeConfigRule::NOT_SUPPORTED;
  36     case EmeSessionTypeSupport::SUPPORTED_WITH_IDENTIFIER:
  37       return EmeConfigRule::IDENTIFIER_AND_PERSISTENCE_REQUIRED;
  38     case EmeSessionTypeSupport::SUPPORTED:
  39       return EmeConfigRule::PERSISTENCE_REQUIRED;
  40   }
  41   NOTREACHED();
  42   return EmeConfigRule::NOT_SUPPORTED;
  43 }
  44
  45 static EmeConfigRule GetDistinctiveIdentifierConfigRule(
  46     EmeFeatureSupport support,
  47     EmeFeatureRequirement requirement) {
  48   if (support == EmeFeatureSupport::INVALID) {
  49     NOTREACHED();
  50     return EmeConfigRule::NOT_SUPPORTED;
  51   }
  52
  53   // For NOT_ALLOWED and REQUIRED, the result is as expected. For OPTIONAL, we
  54   // return the most restrictive rule that is not more restrictive than for
  55   // NOT_ALLOWED or REQUIRED. Those values will be checked individually when
  56   // the option is resolved.
  57   //
  58   //                   NOT_ALLOWED    OPTIONAL       REQUIRED
  59   //    NOT_SUPPORTED  I_NOT_ALLOWED  I_NOT_ALLOWED  NOT_SUPPORTED
  60   //      REQUESTABLE  I_NOT_ALLOWED  SUPPORTED      I_REQUIRED
  61   //   ALWAYS_ENABLED  NOT_SUPPORTED  I_REQUIRED     I_REQUIRED
  62   DCHECK(support == EmeFeatureSupport::NOT_SUPPORTED ||
  63          support == EmeFeatureSupport::REQUESTABLE ||
  64          support == EmeFeatureSupport::ALWAYS_ENABLED);
  65   DCHECK(requirement == EmeFeatureRequirement::NotAllowed ||
  66          requirement == EmeFeatureRequirement::Optional ||
  67          requirement == EmeFeatureRequirement::Required);
  68   if ((support == EmeFeatureSupport::NOT_SUPPORTED &&
  69        requirement == EmeFeatureRequirement::Required) ||
  70       (support == EmeFeatureSupport::ALWAYS_ENABLED &&
  71        requirement == EmeFeatureRequirement::NotAllowed)) {
  72     return EmeConfigRule::NOT_SUPPORTED;
  73   }
  74   if (support == EmeFeatureSupport::REQUESTABLE &&
  75       requirement == EmeFeatureRequirement::Optional) {
  76     return EmeConfigRule::SUPPORTED;
  77   }
  78   if (support == EmeFeatureSupport::NOT_SUPPORTED ||
  79       requirement == EmeFeatureRequirement::NotAllowed) {
  80     return EmeConfigRule::IDENTIFIER_NOT_ALLOWED;
  81   }
  82   return EmeConfigRule::IDENTIFIER_REQUIRED;
  83 }
  84
  85 static EmeConfigRule GetPersistentStateConfigRule(
  86     EmeFeatureSupport support,
  87     EmeFeatureRequirement requirement) {
  88   if (support == EmeFeatureSupport::INVALID) {
  89     NOTREACHED();
  90     return EmeConfigRule::NOT_SUPPORTED;
  91   }
  92
  93   // For NOT_ALLOWED and REQUIRED, the result is as expected. For OPTIONAL, we
  94   // return the most restrictive rule that is not more restrictive than for
  95   // NOT_ALLOWED or REQUIRED. Those values will be checked individually when
  96   // the option is resolved.
  97   //
  98   // Note that even though a distinctive identifier can not be required for
  99   // persistent state, it may still be required for persistent sessions.
 100   //
 101   //                   NOT_ALLOWED    OPTIONAL       REQUIRED
 102   //    NOT_SUPPORTED  P_NOT_ALLOWED  P_NOT_ALLOWED  NOT_SUPPORTED
 103   //      REQUESTABLE  P_NOT_ALLOWED  SUPPORTED      P_REQUIRED
 104   //   ALWAYS_ENABLED  NOT_SUPPORTED  P_REQUIRED     P_REQUIRED
 105   DCHECK(support == EmeFeatureSupport::NOT_SUPPORTED ||
 106          support == EmeFeatureSupport::REQUESTABLE ||
 107          support == EmeFeatureSupport::ALWAYS_ENABLED);
 108   DCHECK(requirement == EmeFeatureRequirement::NotAllowed ||
 109          requirement == EmeFeatureRequirement::Optional ||
 110          requirement == EmeFeatureRequirement::Required);
 111   if ((support == EmeFeatureSupport::NOT_SUPPORTED &&
 112        requirement == EmeFeatureRequirement::Required) ||
 113       (support == EmeFeatureSupport::ALWAYS_ENABLED &&
 114        requirement == EmeFeatureRequirement::NotAllowed)) {
 115     return EmeConfigRule::NOT_SUPPORTED;
 116   }
 117   if (support == EmeFeatureSupport::REQUESTABLE &&
 118       requirement == EmeFeatureRequirement::Optional) {
 119     return EmeConfigRule::SUPPORTED;
 120   }
 121   if (support == EmeFeatureSupport::NOT_SUPPORTED ||
 122       requirement == EmeFeatureRequirement::NotAllowed) {
 123     return EmeConfigRule::PERSISTENCE_NOT_ALLOWED;
 124   }
 125   return EmeConfigRule::PERSISTENCE_REQUIRED;
 126 }
 127
 128 }  // namespace
 129
 130 struct KeySystemConfigSelector::SelectionRequest {
 131   std::string key_system;
 132   blink::WebVector<blink::WebMediaKeySystemConfiguration>
 133       candidate_configurations;
 134   blink::WebSecurityOrigin security_origin;
 135   base::Callback<void(const blink::WebMediaKeySystemConfiguration&,
 136                       const CdmConfig&)> succeeded_cb;
 137   base::Callback<void(const blink::WebString&)> not_supported_cb;
 138   bool was_permission_requested = false;
 139   bool is_permission_granted = false;
 140   bool are_secure_codecs_supported = false;
 141 };
 142
 143 // Accumulates configuration rules to determine if a feature (additional
 144 // configuration rule) can be added to an accumulated configuration.
 145 class KeySystemConfigSelector::ConfigState {
 146  public:
 147   ConfigState(bool was_permission_requested, bool is_permission_granted)
 148       : was_permission_requested_(was_permission_requested),
 149         is_permission_granted_(is_permission_granted) {}
 150
 151   bool IsPermissionGranted() const { return is_permission_granted_; }
 152
 153   // Permission is possible if it has not been denied.
 154   bool IsPermissionPossible() const {
 155     return is_permission_granted_ || !was_permission_requested_;
 156   }
 157
 158   bool IsIdentifierRequired() const { return is_identifier_required_; }
 159
 160   bool IsIdentifierRecommended() const { return is_identifier_recommended_; }
 161
 162   bool AreHwSecureCodecsRequired() const {
 163     return are_hw_secure_codecs_required_;
 164   }
 165
 166   // Checks whether a rule is compatible with all previously added rules.
 167   bool IsRuleSupported(EmeConfigRule rule) const {
 168     switch (rule) {
 169       case EmeConfigRule::NOT_SUPPORTED:
 170         return false;
 171       case EmeConfigRule::IDENTIFIER_NOT_ALLOWED:
 172         return !is_identifier_required_;
 173       case EmeConfigRule::IDENTIFIER_REQUIRED:
 174         // TODO(sandersd): Confirm if we should be refusing these rules when
 175         // permission has been denied (as the spec currently says).
 176         return !is_identifier_not_allowed_ && IsPermissionPossible();
 177       case EmeConfigRule::IDENTIFIER_RECOMMENDED:
 178         return true;
 179       case EmeConfigRule::PERSISTENCE_NOT_ALLOWED:
 180         return !is_persistence_required_;
 181       case EmeConfigRule::PERSISTENCE_REQUIRED:
 182         return !is_persistence_not_allowed_;
 183       case EmeConfigRule::IDENTIFIER_AND_PERSISTENCE_REQUIRED:
 184         return (!is_identifier_not_allowed_ && IsPermissionPossible() &&
 185                 !is_persistence_not_allowed_);
 186       case EmeConfigRule::HW_SECURE_CODECS_NOT_ALLOWED:
 187         return !are_hw_secure_codecs_required_;
 188       case EmeConfigRule::HW_SECURE_CODECS_REQUIRED:
 189         return !are_hw_secure_codecs_not_allowed_;
 190       case EmeConfigRule::SUPPORTED:
 191         return true;
 192     }
 193     NOTREACHED();
 194     return false;
 195   }
 196
 197   // Add a rule to the accumulated configuration state.
 198   void AddRule(EmeConfigRule rule) {
 199     DCHECK(IsRuleSupported(rule));
 200     switch (rule) {
 201       case EmeConfigRule::NOT_SUPPORTED:
 202         NOTREACHED();
 203         return;
 204       case EmeConfigRule::IDENTIFIER_NOT_ALLOWED:
 205         is_identifier_not_allowed_ = true;
 206         return;
 207       case EmeConfigRule::IDENTIFIER_REQUIRED:
 208         is_identifier_required_ = true;
 209         return;
 210       case EmeConfigRule::IDENTIFIER_RECOMMENDED:
 211         is_identifier_recommended_ = true;
 212         return;
 213       case EmeConfigRule::PERSISTENCE_NOT_ALLOWED:
 214         is_persistence_not_allowed_ = true;
 215         return;
 216       case EmeConfigRule::PERSISTENCE_REQUIRED:
 217         is_persistence_required_ = true;
 218         return;
 219       case EmeConfigRule::IDENTIFIER_AND_PERSISTENCE_REQUIRED:
 220         is_identifier_required_ = true;
 221         is_persistence_required_ = true;
 222         return;
 223       case EmeConfigRule::HW_SECURE_CODECS_NOT_ALLOWED:
 224         are_hw_secure_codecs_not_allowed_ = true;
 225         return;
 226       case EmeConfigRule::HW_SECURE_CODECS_REQUIRED:
 227         are_hw_secure_codecs_required_ = true;
 228         return;
 229       case EmeConfigRule::SUPPORTED:
 230         return;
 231     }
 232     NOTREACHED();
 233   }
 234
 235  private:
 236   // Whether permission to use a distinctive identifier was requested. If set,
 237   // |is_permission_granted_| represents the final decision.
 238   // (Not changed by adding rules.)
 239   bool was_permission_requested_;
 240
 241   // Whether permission to use a distinctive identifier has been granted.
 242   // (Not changed by adding rules.)
 243   bool is_permission_granted_;
 244
 245   // Whether a rule has been added that requires or blocks a distinctive
 246   // identifier.
 247   bool is_identifier_required_ = false;
 248   bool is_identifier_not_allowed_ = false;
 249
 250   // Whether a rule has been added that recommends a distinctive identifier.
 251   bool is_identifier_recommended_ = false;
 252
 253   // Whether a rule has been added that requires or blocks persistent state.
 254   bool is_persistence_required_ = false;
 255   bool is_persistence_not_allowed_ = false;
 256
 257   // Whether a rule has been added that requires or blocks hardware-secure
 258   // codecs.
 259   bool are_hw_secure_codecs_required_ = false;
 260   bool are_hw_secure_codecs_not_allowed_ = false;
 261 };
 262
 263 KeySystemConfigSelector::KeySystemConfigSelector(
 264     const KeySystems* key_systems,
 265     MediaPermission* media_permission)
 266     : key_systems_(key_systems),
 267       media_permission_(media_permission),
 268       weak_factory_(this) {
 269   DCHECK(key_systems_);
 270   DCHECK(media_permission_);
 271 }
 272
 273 KeySystemConfigSelector::~KeySystemConfigSelector() {
 274 }
 275
 276 bool KeySystemConfigSelector::IsSupportedContentType(
 277     const std::string& key_system,
 278     EmeMediaType media_type,
 279     const std::string& container_mime_type,
 280     const std::string& codecs,
 281     KeySystemConfigSelector::ConfigState* config_state) {
 282   // TODO(sandersd): Move contentType parsing from Blink to here so that invalid
 283   // parameters can be rejected. http://crbug.com/417561
 284   std::string container_lower = base::ToLowerASCII(container_mime_type);
 285
 286   // Check that |container_mime_type| is supported by Chrome.
 287   if (!media::IsSupportedMediaMimeType(container_lower))
 288     return false;
 289
 290   // Check that |codecs| are supported by Chrome. This is done primarily to
 291   // validate extended codecs, but it also ensures that the CDM cannot support
 292   // codecs that Chrome does not (which could complicate the robustness
 293   // algorithm).
 294   std::vector<std::string> codec_vector;
 295   media::ParseCodecString(codecs, &codec_vector, false);
 296   if (!codec_vector.empty() &&
 297       (media::IsSupportedStrictMediaMimeType(container_lower, codec_vector) !=
 298        media::IsSupported)) {
 299     return false;
 300   }
 301
 302   // Check that |container_mime_type| and |codecs| are supported by the CDM.
 303   // This check does not handle extended codecs, so extended codec information
 304   // is stripped (extended codec information was checked above).
 305   std::vector<std::string> stripped_codec_vector;
 306   media::ParseCodecString(codecs, &stripped_codec_vector, true);
 307   EmeConfigRule codecs_rule = key_systems_->GetContentTypeConfigRule(
 308       key_system, media_type, container_lower, stripped_codec_vector);
 309   if (!config_state->IsRuleSupported(codecs_rule))
 310     return false;
 311   config_state->AddRule(codecs_rule);
 312
 313   return true;
 314 }
 315
 316 bool KeySystemConfigSelector::GetSupportedCapabilities(
 317     const std::string& key_system,
 318     EmeMediaType media_type,
 319     const blink::WebVector<blink::WebMediaKeySystemMediaCapability>&
 320         requested_media_capabilities,
 321     KeySystemConfigSelector::ConfigState* config_state,
 322     std::vector<blink::WebMediaKeySystemMediaCapability>*
 323         supported_media_capabilities) {
 324   // From
 325   // https://w3c.github.io/encrypted-media/#get-supported-capabilities-for-media-type
 326   // 1. Let local accumulated capabilities be a local copy of partial
 327   //    configuration.
 328   //    (Skipped as we directly update |config_state|. This is safe because we
 329   //    only do so when at least one requested media capability is supported.)
 330   // 2. Let supported media capabilities be empty.
 331   DCHECK_EQ(supported_media_capabilities->size(), 0ul);
 332   // 3. For each value in requested media capabilities:
 333   for (size_t i = 0; i < requested_media_capabilities.size(); i++) {
 334     // 3.1. Let contentType be the value's contentType member.
 335     // 3.2. Let robustness be the value's robustness member.
 336     const blink::WebMediaKeySystemMediaCapability& capability =
 337         requested_media_capabilities[i];
 338     // 3.3. If contentType is the empty string, return null.
 339     if (capability.mimeType.isEmpty()) {
 340       DVLOG(2) << "Rejecting requested configuration because "
 341                << "a capability contentType was empty.";
 342       return false;
 343     }
 344
 345     // 3.4-3.11. (Implemented by IsSupportedContentType().)
 346     ConfigState proposed_config_state = *config_state;
 347     if (!base::IsStringASCII(capability.mimeType) ||
 348         !base::IsStringASCII(capability.codecs) ||
 349         !IsSupportedContentType(key_system, media_type,
 350                                 base::UTF16ToASCII(
 351                                     base::StringPiece16(capability.mimeType)),
 352                                 base::UTF16ToASCII(
 353                                     base::StringPiece16(capability.codecs)),
 354                                 &proposed_config_state)) {
 355       continue;
 356     }
 357     // 3.12. If robustness is not the empty string, run the following steps:
 358     if (!capability.robustness.isEmpty()) {
 359       // 3.12.1. If robustness is an unrecognized value or not supported by
 360       //         implementation, continue to the next iteration. String
 361       //         comparison is case-sensitive.
 362       if (!base::IsStringASCII(capability.robustness))
 363         continue;
 364       EmeConfigRule robustness_rule = key_systems_->GetRobustnessConfigRule(
 365           key_system, media_type, base::UTF16ToASCII(
 366               base::StringPiece16(capability.robustness)));
 367       if (!proposed_config_state.IsRuleSupported(robustness_rule))
 368         continue;
 369       proposed_config_state.AddRule(robustness_rule);
 370       // 3.12.2. Add robustness to configuration.
 371       //         (It's already added, we use capability as configuration.)
 372     }
 373     // 3.13. If the user agent and implementation do not support playback of
 374     //       encrypted media data as specified by configuration, including all
 375     //       media types, in combination with local accumulated capabilities,
 376     //       continue to the next iteration.
 377     //       (This is handled when adding rules to |proposed_config_state|.)
 378     // 3.14. Add configuration to supported media capabilities.
 379     supported_media_capabilities->push_back(capability);
 380     // 3.15. Add configuration to local accumulated capabilities.
 381     *config_state = proposed_config_state;
 382   }
 383   // 4. If supported media capabilities is empty, return null.
 384   if (supported_media_capabilities->empty()) {
 385     DVLOG(2) << "Rejecting requested configuration because "
 386              << "no capabilities were supported.";
 387     return false;
 388   }
 389   // 5. Return media type capabilities.
 390   return true;
 391 }
 392
 393 KeySystemConfigSelector::ConfigurationSupport
 394 KeySystemConfigSelector::GetSupportedConfiguration(
 395     const std::string& key_system,
 396     const blink::WebMediaKeySystemConfiguration& candidate,
 397     ConfigState* config_state,
 398     blink::WebMediaKeySystemConfiguration* accumulated_configuration) {
 399   // From https://w3c.github.io/encrypted-media/#get-supported-configuration
 400   // 1. Let accumulated configuration be empty. (Done by caller.)
 401   // 2. If the initDataTypes member is present in candidate configuration, run
 402   //    the following steps:
 403   if (candidate.hasInitDataTypes) {
 404     // 2.1. Let supported types be empty.
 405     std::vector<blink::WebEncryptedMediaInitDataType> supported_types;
 406
 407     // 2.2. For each value in candidate configuration's initDataTypes member:
 408     for (size_t i = 0; i < candidate.initDataTypes.size(); i++) {
 409       // 2.2.1. Let initDataType be the value.
 410       blink::WebEncryptedMediaInitDataType init_data_type =
 411           candidate.initDataTypes[i];
 412       // 2.2.2. If the implementation supports generating requests based on
 413       //        initDataType, add initDataType to supported types. String
 414       //        comparison is case-sensitive. The empty string is never
 415       //        supported.
 416       if (key_systems_->IsSupportedInitDataType(
 417               key_system, ConvertToEmeInitDataType(init_data_type))) {
 418         supported_types.push_back(init_data_type);
 419       }
 420     }
 421
 422     // 2.3. If supported types is empty, return null.
 423     if (supported_types.empty()) {
 424       DVLOG(2) << "Rejecting requested configuration because "
 425                << "no initDataType values were supported.";
 426       return CONFIGURATION_NOT_SUPPORTED;
 427     }
 428
 429     // 2.4. Add supported types to accumulated configuration.
 430     accumulated_configuration->initDataTypes = supported_types;
 431   }
 432
 433   // 3. Follow the steps for the value of candidate configuration's
 434   //    distinctiveIdentifier member from the following list:
 435   //      - "required": If the implementation does not support a persistent
 436   //        Distinctive Identifier in combination with accumulated
 437   //        configuration, return null.
 438   //      - "optional": Continue.
 439   //      - "not-allowed": If the implementation requires a Distinctive
 440   //        Identifier in combination with accumulated configuration, return
 441   //        null.
 442   // We also reject OPTIONAL when distinctive identifiers are ALWAYS_ENABLED and
 443   // permission has already been denied. This would happen anyway at step 11.
 444   EmeConfigRule di_rule = GetDistinctiveIdentifierConfigRule(
 445       key_systems_->GetDistinctiveIdentifierSupport(key_system),
 446       candidate.distinctiveIdentifier);
 447   if (!config_state->IsRuleSupported(di_rule)) {
 448     DVLOG(2) << "Rejecting requested configuration because "
 449              << "the distinctiveIdentifier requirement was not supported.";
 450     return CONFIGURATION_NOT_SUPPORTED;
 451   }
 452   config_state->AddRule(di_rule);
 453
 454   // 4. Add the value of the candidate configuration's distinctiveIdentifier
 455   //    member to accumulated configuration.
 456   accumulated_configuration->distinctiveIdentifier =
 457       candidate.distinctiveIdentifier;
 458
 459   // 5. Follow the steps for the value of candidate configuration's
 460   //    persistentState member from the following list:
 461   //      - "required": If the implementation does not support persisting state
 462   //        in combination with accumulated configuration, return null.
 463   //      - "optional": Continue.
 464   //      - "not-allowed": If the implementation requires persisting state in
 465   //        combination with accumulated configuration, return null.
 466   EmeConfigRule ps_rule = GetPersistentStateConfigRule(
 467       key_systems_->GetPersistentStateSupport(key_system),
 468       candidate.persistentState);
 469   if (!config_state->IsRuleSupported(ps_rule)) {
 470     DVLOG(2) << "Rejecting requested configuration because "
 471              << "the persistentState requirement was not supported.";
 472     return CONFIGURATION_NOT_SUPPORTED;
 473   }
 474   config_state->AddRule(ps_rule);
 475
 476   // 6. Add the value of the candidate configuration's persistentState
 477   //    member to accumulated configuration.
 478   accumulated_configuration->persistentState = candidate.persistentState;
 479
 480   // 7. Follow the steps for the first matching condition from the following
 481   //    list:
 482   //      - If the sessionTypes member is present in candidate configuration,
 483   //        let session types be candidate configuration's sessionTypes member.
 484   //      - Otherwise, let session types be [ "temporary" ].
 485   blink::WebVector<blink::WebEncryptedMediaSessionType> session_types;
 486   if (candidate.hasSessionTypes) {
 487     session_types = candidate.sessionTypes;
 488   } else {
 489     std::vector<blink::WebEncryptedMediaSessionType> temporary(1);
 490     temporary[0] = blink::WebEncryptedMediaSessionType::Temporary;
 491     session_types = temporary;
 492   }
 493
 494   // 8. For each value in session types:
 495   for (size_t i = 0; i < session_types.size(); i++) {
 496     // 8.1. Let session type be the value.
 497     blink::WebEncryptedMediaSessionType session_type = session_types[i];
 498     // 8.2. If the implementation does not support session type in combination
 499     //      with accumulated configuration, return null.
 500     // 8.3. If session type is "persistent-license" or
 501     //      "persistent-release-message", follow the steps for accumulated
 502     //      configuration's persistentState value from the following list:
 503     //        - "required": Continue.
 504     //        - "optional": Change accumulated configuration's persistentState
 505     //          value to "required".
 506     //        - "not-allowed": Return null.
 507     EmeConfigRule session_type_rule = EmeConfigRule::NOT_SUPPORTED;
 508     switch (session_type) {
 509       case blink::WebEncryptedMediaSessionType::Unknown:
 510         DVLOG(2) << "Rejecting requested configuration because "
 511                  << "a required session type was not recognized.";
 512         return CONFIGURATION_NOT_SUPPORTED;
 513       case blink::WebEncryptedMediaSessionType::Temporary:
 514         session_type_rule = EmeConfigRule::SUPPORTED;
 515         break;
 516       case blink::WebEncryptedMediaSessionType::PersistentLicense:
 517         session_type_rule = GetSessionTypeConfigRule(
 518             key_systems_->GetPersistentLicenseSessionSupport(key_system));
 519         break;
 520       case blink::WebEncryptedMediaSessionType::PersistentReleaseMessage:
 521         session_type_rule = GetSessionTypeConfigRule(
 522             key_systems_->GetPersistentReleaseMessageSessionSupport(
 523                 key_system));
 524         break;
 525     }
 526     if (!config_state->IsRuleSupported(session_type_rule)) {
 527       DVLOG(2) << "Rejecting requested configuration because "
 528                << "a required session type was not supported.";
 529       return CONFIGURATION_NOT_SUPPORTED;
 530     }
 531     config_state->AddRule(session_type_rule);
 532   }
 533
 534   // 9. Add session types to accumulated configuration.
 535   accumulated_configuration->sessionTypes = session_types;
 536
 537   // 10. If the videoCapabilities member is present in candidate configuration:
 538   if (candidate.hasVideoCapabilities) {
 539     // 10.1. Let video capabilities be the result of executing the Get Supported
 540     //       Capabilities for Media Type algorithm on Video, candidate
 541     //       configuration's videoCapabilities member, and accumulated
 542     //       configuration.
 543     // 10.2. If video capabilities is null, return null.
 544     std::vector<blink::WebMediaKeySystemMediaCapability> video_capabilities;
 545     if (!GetSupportedCapabilities(key_system, EmeMediaType::VIDEO,
 546                                   candidate.videoCapabilities, config_state,
 547                                   &video_capabilities)) {
 548       return CONFIGURATION_NOT_SUPPORTED;
 549     }
 550
 551     // 10.3. Add video capabilities to accumulated configuration.
 552     accumulated_configuration->videoCapabilities = video_capabilities;
 553   }
 554
 555   // 11. If the audioCapabilities member is present in candidate configuration:
 556   if (candidate.hasAudioCapabilities) {
 557     // 11.1. Let audio capabilities be the result of executing the Get Supported
 558     //       Capabilities for Media Type algorithm on Audio, candidate
 559     //       configuration's audioCapabilities member, and accumulated
 560     //       configuration.
 561     // 11.2. If audio capabilities is null, return null.
 562     std::vector<blink::WebMediaKeySystemMediaCapability> audio_capabilities;
 563     if (!GetSupportedCapabilities(key_system, EmeMediaType::AUDIO,
 564                                   candidate.audioCapabilities, config_state,
 565                                   &audio_capabilities)) {
 566       return CONFIGURATION_NOT_SUPPORTED;
 567     }
 568
 569     // 11.3. Add audio capabilities to accumulated configuration.
 570     accumulated_configuration->audioCapabilities = audio_capabilities;
 571   }
 572
 573   // 12. If accumulated configuration's distinctiveIdentifier value is
 574   //     "optional", follow the steps for the first matching condition from the
 575   //     following list:
 576   //       - If the implementation requires a Distinctive Identifier for any of
 577   //         the combinations in accumulated configuration, change accumulated
 578   //         configuration's distinctiveIdentifier value to "required".
 579   //       - Otherwise, change accumulated configuration's distinctiveIdentifier
 580   //         value to "not-allowed".
 581   if (accumulated_configuration->distinctiveIdentifier ==
 582       blink::WebMediaKeySystemConfiguration::Requirement::Optional) {
 583     EmeConfigRule not_allowed_rule = GetDistinctiveIdentifierConfigRule(
 584         key_systems_->GetDistinctiveIdentifierSupport(key_system),
 585         EmeFeatureRequirement::NotAllowed);
 586     EmeConfigRule required_rule = GetDistinctiveIdentifierConfigRule(
 587         key_systems_->GetDistinctiveIdentifierSupport(key_system),
 588         EmeFeatureRequirement::Required);
 589     bool not_allowed_supported =
 590         config_state->IsRuleSupported(not_allowed_rule);
 591     bool required_supported = config_state->IsRuleSupported(required_rule);
 592     // If a distinctive identifier is recommend and that is a possible outcome,
 593     // prefer that.
 594     if (required_supported && config_state->IsIdentifierRecommended() &&
 595         config_state->IsPermissionPossible()) {
 596       not_allowed_supported = false;
 597     }
 598     if (not_allowed_supported) {
 599       accumulated_configuration->distinctiveIdentifier =
 600           blink::WebMediaKeySystemConfiguration::Requirement::NotAllowed;
 601       config_state->AddRule(not_allowed_rule);
 602     } else if (required_supported) {
 603       accumulated_configuration->distinctiveIdentifier =
 604           blink::WebMediaKeySystemConfiguration::Requirement::Required;
 605       config_state->AddRule(required_rule);
 606     } else {
 607       // We should not have passed step 3.
 608       NOTREACHED();
 609       return CONFIGURATION_NOT_SUPPORTED;
 610     }
 611   }
 612
 613   // 13. If accumulated configuration's persistentState value is "optional",
 614   //     follow the steps for the first matching condition from the following
 615   //     list:
 616   //       - If the implementation requires persisting state for any of the
 617   //         combinations in accumulated configuration, change accumulated
 618   //         configuration's persistentState value to "required".
 619   //       - Otherwise, change accumulated configuration's persistentState value
 620   //         to "not-allowed".
 621   if (accumulated_configuration->persistentState ==
 622       blink::WebMediaKeySystemConfiguration::Requirement::Optional) {
 623     EmeConfigRule not_allowed_rule = GetPersistentStateConfigRule(
 624         key_systems_->GetPersistentStateSupport(key_system),
 625         EmeFeatureRequirement::NotAllowed);
 626     EmeConfigRule required_rule = GetPersistentStateConfigRule(
 627         key_systems_->GetPersistentStateSupport(key_system),
 628         EmeFeatureRequirement::Required);
 629     // |distinctiveIdentifier| should not be affected after it is decided.
 630     DCHECK(not_allowed_rule == EmeConfigRule::NOT_SUPPORTED ||
 631            not_allowed_rule == EmeConfigRule::PERSISTENCE_NOT_ALLOWED);
 632     DCHECK(required_rule == EmeConfigRule::NOT_SUPPORTED ||
 633            required_rule == EmeConfigRule::PERSISTENCE_REQUIRED);
 634     bool not_allowed_supported =
 635         config_state->IsRuleSupported(not_allowed_rule);
 636     bool required_supported = config_state->IsRuleSupported(required_rule);
 637     if (not_allowed_supported) {
 638       accumulated_configuration->persistentState =
 639           blink::WebMediaKeySystemConfiguration::Requirement::NotAllowed;
 640       config_state->AddRule(not_allowed_rule);
 641     } else if (required_supported) {
 642       accumulated_configuration->persistentState =
 643           blink::WebMediaKeySystemConfiguration::Requirement::Required;
 644       config_state->AddRule(required_rule);
 645     } else {
 646       // We should not have passed step 5.
 647       NOTREACHED();
 648       return CONFIGURATION_NOT_SUPPORTED;
 649     }
 650   }
 651
 652   // 14. If implementation in the configuration specified by the combination of
 653   //     the values in accumulated configuration is not supported or not allowed
 654   //     in the origin, return null.
 655   // 15. If accumulated configuration's distinctiveIdentifier value is
 656   //     "required", [prompt the user for consent].
 657   if (accumulated_configuration->distinctiveIdentifier ==
 658       blink::WebMediaKeySystemConfiguration::Requirement::Required) {
 659     // The caller is responsible for resolving what to do if permission is
 660     // required but has been denied (it should treat it as NOT_SUPPORTED).
 661     if (!config_state->IsPermissionGranted())
 662       return CONFIGURATION_REQUIRES_PERMISSION;
 663   }
 664
 665   // 16. If the label member is present in candidate configuration, add the
 666   //     value of the candidate configuration's label member to accumulated
 667   //     configuration.
 668   accumulated_configuration->label = candidate.label;
 669
 670   // 17. Return accumulated configuration.
 671   return CONFIGURATION_SUPPORTED;
 672 }
 673
 674 void KeySystemConfigSelector::SelectConfig(
 675     const blink::WebString& key_system,
 676     const blink::WebVector<blink::WebMediaKeySystemConfiguration>&
 677         candidate_configurations,
 678     const blink::WebSecurityOrigin& security_origin,
 679     bool are_secure_codecs_supported,
 680     base::Callback<void(const blink::WebMediaKeySystemConfiguration&,
 681                         const CdmConfig&)> succeeded_cb,
 682     base::Callback<void(const blink::WebString&)> not_supported_cb) {
 683   // Continued from requestMediaKeySystemAccess(), step 7, from
 684   // https://w3c.github.io/encrypted-media/#requestmediakeysystemaccess
 685   //
 686   // 7.1. If keySystem is not one of the Key Systems supported by the user
 687   //      agent, reject promise with with a new DOMException whose name is
 688   //      NotSupportedError. String comparison is case-sensitive.
 689   if (!base::IsStringASCII(key_system)) {
 690     not_supported_cb.Run("Only ASCII keySystems are supported");
 691     return;
 692   }
 693
 694   std::string key_system_ascii =
 695       base::UTF16ToASCII(base::StringPiece16(key_system));
 696   if (!key_systems_->IsSupportedKeySystem(key_system_ascii)) {
 697     not_supported_cb.Run("Unsupported keySystem");
 698     return;
 699   }
 700
 701   // 7.2-7.4. Implemented by OnSelectConfig().
 702   // TODO(sandersd): This should be async, ideally not on the main thread.
 703   scoped_ptr<SelectionRequest> request(new SelectionRequest());
 704   request->key_system = key_system_ascii;
 705   request->candidate_configurations = candidate_configurations;
 706   request->security_origin = security_origin;
 707   request->are_secure_codecs_supported = are_secure_codecs_supported;
 708   request->succeeded_cb = succeeded_cb;
 709   request->not_supported_cb = not_supported_cb;
 710   SelectConfigInternal(request.Pass());
 711 }
 712
 713 void KeySystemConfigSelector::SelectConfigInternal(
 714     scoped_ptr<SelectionRequest> request) {
 715   // Continued from requestMediaKeySystemAccess(), step 7.1, from
 716   // https://w3c.github.io/encrypted-media/#requestmediakeysystemaccess
 717   //
 718   // 7.2. Let implementation be the implementation of keySystem.
 719   //      (|key_systems_| fills this role.)
 720   // 7.3. For each value in supportedConfigurations:
 721   for (size_t i = 0; i < request->candidate_configurations.size(); i++) {
 722     // 7.3.1. Let candidate configuration be the value.
 723     // 7.3.2. Let supported configuration be the result of executing the Get
 724     //        Supported Configuration algorithm on implementation, candidate
 725     //        configuration, and origin.
 726     // 7.3.3. If supported configuration is not null, [initialize and return a
 727     //        new MediaKeySystemAccess object.]
 728     ConfigState config_state(request->was_permission_requested,
 729                              request->is_permission_granted);
 730     DCHECK(config_state.IsRuleSupported(
 731         EmeConfigRule::HW_SECURE_CODECS_NOT_ALLOWED));
 732     if (!request->are_secure_codecs_supported)
 733       config_state.AddRule(EmeConfigRule::HW_SECURE_CODECS_NOT_ALLOWED);
 734     blink::WebMediaKeySystemConfiguration accumulated_configuration;
 735     CdmConfig cdm_config;
 736     ConfigurationSupport support = GetSupportedConfiguration(
 737         request->key_system, request->candidate_configurations[i],
 738         &config_state, &accumulated_configuration);
 739     switch (support) {
 740       case CONFIGURATION_NOT_SUPPORTED:
 741         continue;
 742       case CONFIGURATION_REQUIRES_PERMISSION:
 743         if (request->was_permission_requested) {
 744           DVLOG(2) << "Rejecting requested configuration because "
 745                    << "permission was denied.";
 746           continue;
 747         }
 748         {
 749           // Note: the GURL must not be constructed inline because
 750           // base::Passed(&request) sets |request| to null.
 751           GURL security_origin(request->security_origin.toString());
 752           media_permission_->RequestPermission(
 753               MediaPermission::PROTECTED_MEDIA_IDENTIFIER, security_origin,
 754               base::Bind(&KeySystemConfigSelector::OnPermissionResult,
 755                          weak_factory_.GetWeakPtr(), base::Passed(&request)));
 756         }
 757         return;
 758       case CONFIGURATION_SUPPORTED:
 759         cdm_config.allow_distinctive_identifier =
 760             (accumulated_configuration.distinctiveIdentifier ==
 761              blink::WebMediaKeySystemConfiguration::Requirement::Required);
 762         cdm_config.allow_persistent_state =
 763             (accumulated_configuration.persistentState ==
 764              blink::WebMediaKeySystemConfiguration::Requirement::Required);
 765         cdm_config.use_hw_secure_codecs =
 766             config_state.AreHwSecureCodecsRequired();
 767         request->succeeded_cb.Run(accumulated_configuration, cdm_config);
 768         return;
 769     }
 770   }
 771
 772   // 7.4. Reject promise with a new DOMException whose name is
 773   //      NotSupportedError.
 774   request->not_supported_cb.Run(
 775       "None of the requested configurations were supported.");
 776 }
 777
 778 void KeySystemConfigSelector::OnPermissionResult(
 779     scoped_ptr<SelectionRequest> request,
 780     bool is_permission_granted) {
 781   request->was_permission_requested = true;
 782   request->is_permission_granted = is_permission_granted;
 783   SelectConfigInternal(request.Pass());
 784 }
 785
 786 }  // namespace media