chrome/browser/extensions/user_script_loader.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 "chrome/browser/extensions/user_script_loader.h"
   6
   7 #include <set>
   8 #include <string>
   9
  10 #include "base/bind.h"
  11 #include "base/bind_helpers.h"
  12 #include "base/files/file_path.h"
  13 #include "base/files/file_util.h"
  14 #include "base/memory/shared_memory.h"
  15 #include "base/version.h"
  16 #include "chrome/browser/chrome_notification_types.h"
  17 #include "chrome/browser/profiles/profile.h"
  18 #include "chrome/common/extensions/api/i18n/default_locale_handler.h"
  19 #include "content/public/browser/browser_thread.h"
  20 #include "content/public/browser/notification_service.h"
  21 #include "content/public/browser/render_process_host.h"
  22 #include "extensions/browser/component_extension_resource_manager.h"
  23 #include "extensions/browser/content_verifier.h"
  24 #include "extensions/browser/extension_registry.h"
  25 #include "extensions/browser/extension_system.h"
  26 #include "extensions/browser/extensions_browser_client.h"
  27 #include "extensions/common/extension_messages.h"
  28 #include "extensions/common/file_util.h"
  29 #include "extensions/common/message_bundle.h"
  30 #include "extensions/common/one_shot_event.h"
  31 #include "ui/base/resource/resource_bundle.h"
  32
  33 using content::BrowserThread;
  34 using extensions::ExtensionsBrowserClient;
  35
  36 namespace extensions {
  37
  38 namespace {
  39
  40 typedef base::Callback<
  41     void(scoped_ptr<UserScriptList>, scoped_ptr<base::SharedMemory>)>
  42     LoadScriptsCallback;
  43
  44 void VerifyContent(scoped_refptr<ContentVerifier> verifier,
  45                    const ExtensionId& extension_id,
  46                    const base::FilePath& extension_root,
  47                    const base::FilePath& relative_path,
  48                    const std::string& content) {
  49   DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
  50   scoped_refptr<ContentVerifyJob> job(
  51       verifier->CreateJobFor(extension_id, extension_root, relative_path));
  52   if (job.get()) {
  53     job->Start();
  54     job->BytesRead(content.size(), content.data());
  55     job->DoneReading();
  56   }
  57 }
  58
  59 bool LoadScriptContent(const ExtensionId& extension_id,
  60                        UserScript::File* script_file,
  61                        const SubstitutionMap* localization_messages,
  62                        scoped_refptr<ContentVerifier> verifier) {
  63   std::string content;
  64   const base::FilePath& path = ExtensionResource::GetFilePath(
  65       script_file->extension_root(),
  66       script_file->relative_path(),
  67       ExtensionResource::SYMLINKS_MUST_RESOLVE_WITHIN_ROOT);
  68   if (path.empty()) {
  69     int resource_id;
  70     if (ExtensionsBrowserClient::Get()->GetComponentExtensionResourceManager()->
  71         IsComponentExtensionResource(script_file->extension_root(),
  72                                      script_file->relative_path(),
  73                                      &resource_id)) {
  74       const ResourceBundle& rb = ResourceBundle::GetSharedInstance();
  75       content = rb.GetRawDataResource(resource_id).as_string();
  76     } else {
  77       LOG(WARNING) << "Failed to get file path to "
  78                    << script_file->relative_path().value() << " from "
  79                    << script_file->extension_root().value();
  80       return false;
  81     }
  82   } else {
  83     if (!base::ReadFileToString(path, &content)) {
  84       LOG(WARNING) << "Failed to load user script file: " << path.value();
  85       return false;
  86     }
  87     if (verifier.get()) {
  88       content::BrowserThread::PostTask(content::BrowserThread::IO,
  89                                        FROM_HERE,
  90                                        base::Bind(&VerifyContent,
  91                                                   verifier,
  92                                                   extension_id,
  93                                                   script_file->extension_root(),
  94                                                   script_file->relative_path(),
  95                                                   content));
  96     }
  97   }
  98
  99   // Localize the content.
 100   if (localization_messages) {
 101     std::string error;
 102     MessageBundle::ReplaceMessagesWithExternalDictionary(
 103         *localization_messages, &content, &error);
 104     if (!error.empty()) {
 105       LOG(WARNING) << "Failed to replace messages in script: " << error;
 106     }
 107   }
 108
 109   // Remove BOM from the content.
 110   std::string::size_type index = content.find(base::kUtf8ByteOrderMark);
 111   if (index == 0) {
 112     script_file->set_content(content.substr(strlen(base::kUtf8ByteOrderMark)));
 113   } else {
 114     script_file->set_content(content);
 115   }
 116
 117   return true;
 118 }
 119
 120 SubstitutionMap* GetLocalizationMessages(const ExtensionsInfo& extensions_info,
 121                                          const ExtensionId& extension_id) {
 122   ExtensionsInfo::const_iterator iter = extensions_info.find(extension_id);
 123   if (iter == extensions_info.end())
 124     return NULL;
 125   return file_util::LoadMessageBundleSubstitutionMap(
 126       iter->second.first, extension_id, iter->second.second);
 127 }
 128
 129 void LoadUserScripts(UserScriptList* user_scripts,
 130                      const ExtensionsInfo& extensions_info,
 131                      const std::set<int>& added_script_ids,
 132                      ContentVerifier* verifier) {
 133   for (UserScriptList::iterator script = user_scripts->begin();
 134        script != user_scripts->end();
 135        ++script) {
 136     if (added_script_ids.count(script->id()) == 0)
 137       continue;
 138     scoped_ptr<SubstitutionMap> localization_messages(
 139         GetLocalizationMessages(extensions_info, script->extension_id()));
 140     for (size_t k = 0; k < script->js_scripts().size(); ++k) {
 141       UserScript::File& script_file = script->js_scripts()[k];
 142       if (script_file.GetContent().empty())
 143         LoadScriptContent(script->extension_id(), &script_file, NULL, verifier);
 144     }
 145     for (size_t k = 0; k < script->css_scripts().size(); ++k) {
 146       UserScript::File& script_file = script->css_scripts()[k];
 147       if (script_file.GetContent().empty())
 148         LoadScriptContent(script->extension_id(),
 149                           &script_file,
 150                           localization_messages.get(),
 151                           verifier);
 152     }
 153   }
 154 }
 155
 156 // Pickle user scripts and return pointer to the shared memory.
 157 scoped_ptr<base::SharedMemory> Serialize(const UserScriptList& scripts) {
 158   Pickle pickle;
 159   pickle.WriteSizeT(scripts.size());
 160   for (UserScriptList::const_iterator script = scripts.begin();
 161        script != scripts.end();
 162        ++script) {
 163     // TODO(aa): This can be replaced by sending content script metadata to
 164     // renderers along with other extension data in ExtensionMsg_Loaded.
 165     // See crbug.com/70516.
 166     script->Pickle(&pickle);
 167     // Write scripts as 'data' so that we can read it out in the slave without
 168     // allocating a new string.
 169     for (size_t j = 0; j < script->js_scripts().size(); j++) {
 170       base::StringPiece contents = script->js_scripts()[j].GetContent();
 171       pickle.WriteData(contents.data(), contents.length());
 172     }
 173     for (size_t j = 0; j < script->css_scripts().size(); j++) {
 174       base::StringPiece contents = script->css_scripts()[j].GetContent();
 175       pickle.WriteData(contents.data(), contents.length());
 176     }
 177   }
 178
 179   // Create the shared memory object.
 180   base::SharedMemory shared_memory;
 181
 182   base::SharedMemoryCreateOptions options;
 183   options.size = pickle.size();
 184   options.share_read_only = true;
 185   if (!shared_memory.Create(options))
 186     return scoped_ptr<base::SharedMemory>();
 187
 188   if (!shared_memory.Map(pickle.size()))
 189     return scoped_ptr<base::SharedMemory>();
 190
 191   // Copy the pickle to shared memory.
 192   memcpy(shared_memory.memory(), pickle.data(), pickle.size());
 193
 194   base::SharedMemoryHandle readonly_handle;
 195   if (!shared_memory.ShareReadOnlyToProcess(base::GetCurrentProcessHandle(),
 196                                             &readonly_handle))
 197     return scoped_ptr<base::SharedMemory>();
 198
 199   return make_scoped_ptr(new base::SharedMemory(readonly_handle,
 200                                                 /*read_only=*/true));
 201 }
 202
 203 void LoadScriptsOnFileThread(scoped_ptr<UserScriptList> user_scripts,
 204                              const ExtensionsInfo& extensions_info,
 205                              const std::set<int>& added_script_ids,
 206                              scoped_refptr<ContentVerifier> verifier,
 207                              LoadScriptsCallback callback) {
 208   DCHECK(user_scripts.get());
 209   LoadUserScripts(
 210       user_scripts.get(), extensions_info, added_script_ids, verifier.get());
 211   scoped_ptr<base::SharedMemory> memory = Serialize(*user_scripts);
 212   BrowserThread::PostTask(
 213       BrowserThread::UI,
 214       FROM_HERE,
 215       base::Bind(callback, base::Passed(&user_scripts), base::Passed(&memory)));
 216 }
 217
 218 // Helper function to parse greasesmonkey headers
 219 bool GetDeclarationValue(const base::StringPiece& line,
 220                          const base::StringPiece& prefix,
 221                          std::string* value) {
 222   base::StringPiece::size_type index = line.find(prefix);
 223   if (index == base::StringPiece::npos)
 224     return false;
 225
 226   std::string temp(line.data() + index + prefix.length(),
 227                    line.length() - index - prefix.length());
 228
 229   if (temp.empty() || !IsWhitespace(temp[0]))
 230     return false;
 231
 232   base::TrimWhitespaceASCII(temp, base::TRIM_ALL, value);
 233   return true;
 234 }
 235
 236 }  // namespace
 237
 238 // static
 239 bool UserScriptLoader::ParseMetadataHeader(const base::StringPiece& script_text,
 240                                            UserScript* script) {
 241   // http://wiki.greasespot.net/Metadata_block
 242   base::StringPiece line;
 243   size_t line_start = 0;
 244   size_t line_end = line_start;
 245   bool in_metadata = false;
 246
 247   static const base::StringPiece kUserScriptBegin("// ==UserScript==");
 248   static const base::StringPiece kUserScriptEng("// ==/UserScript==");
 249   static const base::StringPiece kNamespaceDeclaration("// @namespace");
 250   static const base::StringPiece kNameDeclaration("// @name");
 251   static const base::StringPiece kVersionDeclaration("// @version");
 252   static const base::StringPiece kDescriptionDeclaration("// @description");
 253   static const base::StringPiece kIncludeDeclaration("// @include");
 254   static const base::StringPiece kExcludeDeclaration("// @exclude");
 255   static const base::StringPiece kMatchDeclaration("// @match");
 256   static const base::StringPiece kExcludeMatchDeclaration("// @exclude_match");
 257   static const base::StringPiece kRunAtDeclaration("// @run-at");
 258   static const base::StringPiece kRunAtDocumentStartValue("document-start");
 259   static const base::StringPiece kRunAtDocumentEndValue("document-end");
 260   static const base::StringPiece kRunAtDocumentIdleValue("document-idle");
 261
 262   while (line_start < script_text.length()) {
 263     line_end = script_text.find('\n', line_start);
 264
 265     // Handle the case where there is no trailing newline in the file.
 266     if (line_end == std::string::npos)
 267       line_end = script_text.length() - 1;
 268
 269     line.set(script_text.data() + line_start, line_end - line_start);
 270
 271     if (!in_metadata) {
 272       if (line.starts_with(kUserScriptBegin))
 273         in_metadata = true;
 274     } else {
 275       if (line.starts_with(kUserScriptEng))
 276         break;
 277
 278       std::string value;
 279       if (GetDeclarationValue(line, kIncludeDeclaration, &value)) {
 280         // We escape some characters that MatchPattern() considers special.
 281         ReplaceSubstringsAfterOffset(&value, 0, "\\", "\\\\");
 282         ReplaceSubstringsAfterOffset(&value, 0, "?", "\\?");
 283         script->add_glob(value);
 284       } else if (GetDeclarationValue(line, kExcludeDeclaration, &value)) {
 285         ReplaceSubstringsAfterOffset(&value, 0, "\\", "\\\\");
 286         ReplaceSubstringsAfterOffset(&value, 0, "?", "\\?");
 287         script->add_exclude_glob(value);
 288       } else if (GetDeclarationValue(line, kNamespaceDeclaration, &value)) {
 289         script->set_name_space(value);
 290       } else if (GetDeclarationValue(line, kNameDeclaration, &value)) {
 291         script->set_name(value);
 292       } else if (GetDeclarationValue(line, kVersionDeclaration, &value)) {
 293         Version version(value);
 294         if (version.IsValid())
 295           script->set_version(version.GetString());
 296       } else if (GetDeclarationValue(line, kDescriptionDeclaration, &value)) {
 297         script->set_description(value);
 298       } else if (GetDeclarationValue(line, kMatchDeclaration, &value)) {
 299         URLPattern pattern(UserScript::ValidUserScriptSchemes());
 300         if (URLPattern::PARSE_SUCCESS != pattern.Parse(value))
 301           return false;
 302         script->add_url_pattern(pattern);
 303       } else if (GetDeclarationValue(line, kExcludeMatchDeclaration, &value)) {
 304         URLPattern exclude(UserScript::ValidUserScriptSchemes());
 305         if (URLPattern::PARSE_SUCCESS != exclude.Parse(value))
 306           return false;
 307         script->add_exclude_url_pattern(exclude);
 308       } else if (GetDeclarationValue(line, kRunAtDeclaration, &value)) {
 309         if (value == kRunAtDocumentStartValue)
 310           script->set_run_location(UserScript::DOCUMENT_START);
 311         else if (value == kRunAtDocumentEndValue)
 312           script->set_run_location(UserScript::DOCUMENT_END);
 313         else if (value == kRunAtDocumentIdleValue)
 314           script->set_run_location(UserScript::DOCUMENT_IDLE);
 315         else
 316           return false;
 317       }
 318
 319       // TODO(aa): Handle more types of metadata.
 320     }
 321
 322     line_start = line_end + 1;
 323   }
 324
 325   // If no patterns were specified, default to @include *. This is what
 326   // Greasemonkey does.
 327   if (script->globs().empty() && script->url_patterns().is_empty())
 328     script->add_glob("*");
 329
 330   return true;
 331 }
 332
 333 // static
 334 void UserScriptLoader::LoadScriptsForTest(UserScriptList* user_scripts) {
 335   ExtensionsInfo info;
 336   std::set<int> added_script_ids;
 337   for (UserScriptList::iterator it = user_scripts->begin();
 338        it != user_scripts->end();
 339        ++it) {
 340     added_script_ids.insert(it->id());
 341   }
 342   LoadUserScripts(
 343       user_scripts, info, added_script_ids, NULL /* no verifier for testing */);
 344 }
 345
 346 UserScriptLoader::UserScriptLoader(Profile* profile,
 347                                    const ExtensionId& owner_extension_id,
 348                                    bool listen_for_extension_system_loaded)
 349     : user_scripts_(new UserScriptList()),
 350       clear_scripts_(false),
 351       extension_system_ready_(false),
 352       pending_load_(false),
 353       profile_(profile),
 354       owner_extension_id_(owner_extension_id),
 355       extension_registry_observer_(this),
 356       weak_factory_(this) {
 357   extension_registry_observer_.Add(ExtensionRegistry::Get(profile));
 358   if (listen_for_extension_system_loaded) {
 359     ExtensionSystem::Get(profile_)->ready().Post(
 360         FROM_HERE,
 361         base::Bind(&UserScriptLoader::OnExtensionSystemReady,
 362                    weak_factory_.GetWeakPtr()));
 363   } else {
 364     extension_system_ready_ = true;
 365   }
 366   registrar_.Add(this,
 367                  content::NOTIFICATION_RENDERER_PROCESS_CREATED,
 368                  content::NotificationService::AllBrowserContextsAndSources());
 369 }
 370
 371 UserScriptLoader::~UserScriptLoader() {
 372 }
 373
 374 void UserScriptLoader::AddScripts(const std::set<UserScript>& scripts) {
 375   for (std::set<UserScript>::const_iterator it = scripts.begin();
 376        it != scripts.end();
 377        ++it) {
 378     removed_scripts_.erase(*it);
 379     added_scripts_.insert(*it);
 380   }
 381   AttemptLoad();
 382 }
 383
 384 void UserScriptLoader::RemoveScripts(const std::set<UserScript>& scripts) {
 385   for (std::set<UserScript>::const_iterator it = scripts.begin();
 386        it != scripts.end();
 387        ++it) {
 388     added_scripts_.erase(*it);
 389     removed_scripts_.insert(*it);
 390   }
 391   AttemptLoad();
 392 }
 393
 394 void UserScriptLoader::ClearScripts() {
 395   clear_scripts_ = true;
 396   added_scripts_.clear();
 397   removed_scripts_.clear();
 398   AttemptLoad();
 399 }
 400
 401 void UserScriptLoader::Observe(int type,
 402                                const content::NotificationSource& source,
 403                                const content::NotificationDetails& details) {
 404   DCHECK_EQ(type, content::NOTIFICATION_RENDERER_PROCESS_CREATED);
 405   content::RenderProcessHost* process =
 406       content::Source<content::RenderProcessHost>(source).ptr();
 407   Profile* profile = Profile::FromBrowserContext(process->GetBrowserContext());
 408   if (!profile_->IsSameProfile(profile))
 409     return;
 410   if (scripts_ready()) {
 411     SendUpdate(process,
 412                shared_memory_.get(),
 413                std::set<ExtensionId>());  // Include all extensions.
 414   }
 415 }
 416
 417 void UserScriptLoader::OnExtensionUnloaded(
 418     content::BrowserContext* browser_context,
 419     const Extension* extension,
 420     UnloadedExtensionInfo::Reason reason) {
 421   extensions_info_.erase(extension->id());
 422 }
 423
 424 void UserScriptLoader::OnExtensionSystemReady() {
 425   extension_system_ready_ = true;
 426   AttemptLoad();
 427 }
 428
 429 bool UserScriptLoader::ScriptsMayHaveChanged() const {
 430   // Scripts may have changed if there are scripts added, scripts removed, or
 431   // if scripts were cleared and either:
 432   // (1) A load is in progress (which may result in a non-zero number of
 433   //     scripts that need to be cleared), or
 434   // (2) The current set of scripts is non-empty (so they need to be cleared).
 435   return (added_scripts_.size() ||
 436           removed_scripts_.size() ||
 437           (clear_scripts_ &&
 438            (is_loading() || user_scripts_->size())));
 439 }
 440
 441 void UserScriptLoader::AttemptLoad() {
 442   if (extension_system_ready_ && ScriptsMayHaveChanged()) {
 443     if (is_loading())
 444       pending_load_ = true;
 445     else
 446       StartLoad();
 447   }
 448 }
 449
 450 void UserScriptLoader::StartLoad() {
 451   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 452   DCHECK(!is_loading());
 453
 454   // If scripts were marked for clearing before adding and removing, then clear
 455   // them.
 456   if (clear_scripts_) {
 457     user_scripts_->clear();
 458   } else {
 459     for (UserScriptList::iterator it = user_scripts_->begin();
 460          it != user_scripts_->end();) {
 461       if (removed_scripts_.count(*it))
 462         it = user_scripts_->erase(it);
 463       else
 464         ++it;
 465     }
 466   }
 467
 468   user_scripts_->insert(
 469       user_scripts_->end(), added_scripts_.begin(), added_scripts_.end());
 470
 471   std::set<int> added_script_ids;
 472   for (std::set<UserScript>::const_iterator it = added_scripts_.begin();
 473        it != added_scripts_.end();
 474        ++it) {
 475     added_script_ids.insert(it->id());
 476   }
 477
 478   // Expand |changed_extensions_| for OnScriptsLoaded, which will use it in
 479   // its IPC message. This must be done before we clear |added_scripts_| and
 480   // |removed_scripts_| below.
 481   std::set<UserScript> changed_scripts(added_scripts_);
 482   changed_scripts.insert(removed_scripts_.begin(), removed_scripts_.end());
 483   ExpandChangedExtensions(changed_scripts);
 484
 485   // Update |extensions_info_| to contain info from every extension in
 486   // |changed_extensions_| before passing it to LoadScriptsOnFileThread.
 487   UpdateExtensionsInfo();
 488
 489   BrowserThread::PostTask(
 490       BrowserThread::FILE,
 491       FROM_HERE,
 492       base::Bind(&LoadScriptsOnFileThread,
 493                  base::Passed(&user_scripts_),
 494                  extensions_info_,
 495                  added_script_ids,
 496                  make_scoped_refptr(
 497                      ExtensionSystem::Get(profile_)->content_verifier()),
 498                  base::Bind(&UserScriptLoader::OnScriptsLoaded,
 499                             weak_factory_.GetWeakPtr())));
 500
 501   clear_scripts_ = false;
 502   added_scripts_.clear();
 503   removed_scripts_.clear();
 504   user_scripts_.reset(NULL);
 505 }
 506
 507 void UserScriptLoader::OnScriptsLoaded(
 508     scoped_ptr<UserScriptList> user_scripts,
 509     scoped_ptr<base::SharedMemory> shared_memory) {
 510   user_scripts_.reset(user_scripts.release());
 511   if (pending_load_) {
 512     // While we were loading, there were further changes. Don't bother
 513     // notifying about these scripts and instead just immediately reload.
 514     pending_load_ = false;
 515     StartLoad();
 516     return;
 517   }
 518
 519   if (shared_memory.get() == NULL) {
 520     // This can happen if we run out of file descriptors.  In that case, we
 521     // have a choice between silently omitting all user scripts for new tabs,
 522     // by nulling out shared_memory_, or only silently omitting new ones by
 523     // leaving the existing object in place. The second seems less bad, even
 524     // though it removes the possibility that freeing the shared memory block
 525     // would open up enough FDs for long enough for a retry to succeed.
 526
 527     // Pretend the extension change didn't happen.
 528     return;
 529   }
 530
 531   // We've got scripts ready to go.
 532   shared_memory_.reset(shared_memory.release());
 533
 534   for (content::RenderProcessHost::iterator i(
 535            content::RenderProcessHost::AllHostsIterator());
 536        !i.IsAtEnd();
 537        i.Advance()) {
 538     SendUpdate(i.GetCurrentValue(), shared_memory_.get(), changed_extensions_);
 539   }
 540   changed_extensions_.clear();
 541
 542   content::NotificationService::current()->Notify(
 543       extensions::NOTIFICATION_USER_SCRIPTS_UPDATED,
 544       content::Source<Profile>(profile_),
 545       content::Details<base::SharedMemory>(shared_memory_.get()));
 546 }
 547
 548 void UserScriptLoader::SendUpdate(
 549     content::RenderProcessHost* process,
 550     base::SharedMemory* shared_memory,
 551     const std::set<ExtensionId>& changed_extensions) {
 552   // Don't allow injection of content scripts into <webview>.
 553   if (process->IsIsolatedGuest())
 554     return;
 555
 556   Profile* profile = Profile::FromBrowserContext(process->GetBrowserContext());
 557   // Make sure we only send user scripts to processes in our profile.
 558   if (!profile_->IsSameProfile(profile))
 559     return;
 560
 561   // If the process is being started asynchronously, early return.  We'll end up
 562   // calling InitUserScripts when it's created which will call this again.
 563   base::ProcessHandle handle = process->GetHandle();
 564   if (!handle)
 565     return;
 566
 567   base::SharedMemoryHandle handle_for_process;
 568   if (!shared_memory->ShareToProcess(handle, &handle_for_process))
 569     return;  // This can legitimately fail if the renderer asserts at startup.
 570
 571   if (base::SharedMemory::IsHandleValid(handle_for_process)) {
 572     process->Send(new ExtensionMsg_UpdateUserScripts(
 573         handle_for_process, owner_extension_id_, changed_extensions));
 574   }
 575 }
 576
 577 void UserScriptLoader::ExpandChangedExtensions(
 578     const std::set<UserScript>& scripts) {
 579   for (std::set<UserScript>::const_iterator it = scripts.begin();
 580        it != scripts.end();
 581        ++it) {
 582     changed_extensions_.insert(it->extension_id());
 583   }
 584 }
 585
 586 void UserScriptLoader::UpdateExtensionsInfo() {
 587   ExtensionRegistry* registry = ExtensionRegistry::Get(profile_);
 588   for (std::set<ExtensionId>::const_iterator it = changed_extensions_.begin();
 589        it != changed_extensions_.end();
 590        ++it) {
 591     if (extensions_info_.find(*it) == extensions_info_.end()) {
 592       const Extension* extension =
 593           registry->GetExtensionById(*it, ExtensionRegistry::EVERYTHING);
 594       // |changed_extensions_| may include extensions that have been removed,
 595       // which leads to the above lookup failing. In this case, just continue.
 596       if (!extension)
 597         continue;
 598       extensions_info_[*it] = ExtensionSet::ExtensionPathAndDefaultLocale(
 599           extension->path(), LocaleInfo::GetDefaultLocale(extension));
 600     }
 601   }
 602 }
 603
 604 }  // namespace extensions