chrome/browser/extensions/chrome_content_browser_client_extensions_part.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/chrome_content_browser_client_extensions_part.h"
   6
   7 #include <set>
   8
   9 #include "base/command_line.h"
  10 #include "chrome/browser/browser_process.h"
  11 #include "chrome/browser/extensions/browser_permissions_policy_delegate.h"
  12 #include "chrome/browser/extensions/extension_service.h"
  13 #include "chrome/browser/extensions/extension_web_ui.h"
  14 #include "chrome/browser/extensions/extension_webkit_preferences.h"
  15 #include "chrome/browser/media_galleries/fileapi/media_file_system_backend.h"
  16 #include "chrome/browser/profiles/profile.h"
  17 #include "chrome/browser/profiles/profile_io_data.h"
  18 #include "chrome/browser/profiles/profile_manager.h"
  19 #include "chrome/browser/renderer_host/chrome_extension_message_filter.h"
  20 #include "chrome/browser/sync_file_system/local/sync_file_system_backend.h"
  21 #include "chrome/common/chrome_constants.h"
  22 #include "chrome/common/extensions/extension_process_policy.h"
  23 #include "components/guest_view/browser/guest_view_message_filter.h"
  24 #include "content/public/browser/browser_thread.h"
  25 #include "content/public/browser/browser_url_handler.h"
  26 #include "content/public/browser/render_process_host.h"
  27 #include "content/public/browser/render_view_host.h"
  28 #include "content/public/browser/site_instance.h"
  29 #include "content/public/browser/web_contents.h"
  30 #include "content/public/common/content_switches.h"
  31 #include "extensions/browser/api/web_request/web_request_api.h"
  32 #include "extensions/browser/api/web_request/web_request_api_helpers.h"
  33 #include "extensions/browser/extension_host.h"
  34 #include "extensions/browser/extension_message_filter.h"
  35 #include "extensions/browser/extension_registry.h"
  36 #include "extensions/browser/extension_system.h"
  37 #include "extensions/browser/guest_view/extensions_guest_view_message_filter.h"
  38 #include "extensions/browser/guest_view/web_view/web_view_renderer_state.h"
  39 #include "extensions/browser/info_map.h"
  40 #include "extensions/browser/io_thread_extension_message_filter.h"
  41 #include "extensions/browser/view_type_utils.h"
  42 #include "extensions/common/constants.h"
  43 #include "extensions/common/manifest_constants.h"
  44 #include "extensions/common/manifest_handlers/app_isolation_info.h"
  45 #include "extensions/common/manifest_handlers/background_info.h"
  46 #include "extensions/common/manifest_handlers/web_accessible_resources_info.h"
  47 #include "extensions/common/switches.h"
  48
  49 using content::BrowserContext;
  50 using content::BrowserThread;
  51 using content::BrowserURLHandler;
  52 using content::RenderViewHost;
  53 using content::SiteInstance;
  54 using content::WebContents;
  55 using content::WebPreferences;
  56
  57 namespace extensions {
  58
  59 namespace {
  60
  61 // Used by the GetPrivilegeRequiredByUrl() and GetProcessPrivilege() functions
  62 // below.  Extension, and isolated apps require different privileges to be
  63 // granted to their RenderProcessHosts.  This classification allows us to make
  64 // sure URLs are served by hosts with the right set of privileges.
  65 enum RenderProcessHostPrivilege {
  66   PRIV_NORMAL,
  67   PRIV_HOSTED,
  68   PRIV_ISOLATED,
  69   PRIV_EXTENSION,
  70 };
  71
  72 RenderProcessHostPrivilege GetPrivilegeRequiredByUrl(
  73     const GURL& url,
  74     ExtensionRegistry* registry) {
  75   // Default to a normal renderer cause it is lower privileged. This should only
  76   // occur if the URL on a site instance is either malformed, or uninitialized.
  77   // If it is malformed, then there is no need for better privileges anyways.
  78   // If it is uninitialized, but eventually settles on being an a scheme other
  79   // than normal webrenderer, the navigation logic will correct us out of band
  80   // anyways.
  81   if (!url.is_valid())
  82     return PRIV_NORMAL;
  83
  84   if (!url.SchemeIs(kExtensionScheme))
  85     return PRIV_NORMAL;
  86
  87   const Extension* extension =
  88       registry->enabled_extensions().GetByID(url.host());
  89   if (extension && AppIsolationInfo::HasIsolatedStorage(extension))
  90     return PRIV_ISOLATED;
  91   if (extension && extension->is_hosted_app())
  92     return PRIV_HOSTED;
  93   return PRIV_EXTENSION;
  94 }
  95
  96 RenderProcessHostPrivilege GetProcessPrivilege(
  97     content::RenderProcessHost* process_host,
  98     ProcessMap* process_map,
  99     ExtensionRegistry* registry) {
 100   std::set<std::string> extension_ids =
 101       process_map->GetExtensionsInProcess(process_host->GetID());
 102   if (extension_ids.empty())
 103     return PRIV_NORMAL;
 104
 105   for (const std::string& extension_id : extension_ids) {
 106     const Extension* extension =
 107         registry->enabled_extensions().GetByID(extension_id);
 108     if (extension && AppIsolationInfo::HasIsolatedStorage(extension))
 109       return PRIV_ISOLATED;
 110     if (extension && extension->is_hosted_app())
 111       return PRIV_HOSTED;
 112   }
 113
 114   return PRIV_EXTENSION;
 115 }
 116
 117 }  // namespace
 118
 119 ChromeContentBrowserClientExtensionsPart::
 120     ChromeContentBrowserClientExtensionsPart() {
 121   permissions_policy_delegate_.reset(new BrowserPermissionsPolicyDelegate());
 122 }
 123
 124 ChromeContentBrowserClientExtensionsPart::
 125     ~ChromeContentBrowserClientExtensionsPart() {
 126 }
 127
 128 // static
 129 GURL ChromeContentBrowserClientExtensionsPart::GetEffectiveURL(
 130     Profile* profile, const GURL& url) {
 131   // If the input |url| is part of an installed app, the effective URL is an
 132   // extension URL with the ID of that extension as the host. This has the
 133   // effect of grouping apps together in a common SiteInstance.
 134   ExtensionRegistry* registry = ExtensionRegistry::Get(profile);
 135   if (!registry)
 136     return url;
 137
 138   const Extension* extension =
 139       registry->enabled_extensions().GetHostedAppByURL(url);
 140   if (!extension)
 141     return url;
 142
 143   // Bookmark apps do not use the hosted app process model, and should be
 144   // treated as normal URLs.
 145   if (extension->from_bookmark())
 146     return url;
 147
 148   // If the URL is part of an extension's web extent, convert it to an
 149   // extension URL.
 150   return extension->GetResourceURL(url.path());
 151 }
 152
 153 // static
 154 bool ChromeContentBrowserClientExtensionsPart::ShouldUseProcessPerSite(
 155     Profile* profile, const GURL& effective_url) {
 156   if (!effective_url.SchemeIs(kExtensionScheme))
 157     return false;
 158
 159   ExtensionRegistry* registry = ExtensionRegistry::Get(profile);
 160   if (!registry)
 161     return false;
 162
 163   const Extension* extension =
 164       registry->enabled_extensions().GetByID(effective_url.host());
 165   if (!extension)
 166     return false;
 167
 168   // If the URL is part of a hosted app that does not have the background
 169   // permission, or that does not allow JavaScript access to the background
 170   // page, we want to give each instance its own process to improve
 171   // responsiveness.
 172   if (extension->GetType() == Manifest::TYPE_HOSTED_APP) {
 173     if (!extension->permissions_data()->HasAPIPermission(
 174             APIPermission::kBackground) ||
 175         !BackgroundInfo::AllowJSAccess(extension)) {
 176       return false;
 177     }
 178   }
 179
 180   // Hosted apps that have script access to their background page must use
 181   // process per site, since all instances can make synchronous calls to the
 182   // background window.  Other extensions should use process per site as well.
 183   return true;
 184 }
 185
 186 // static
 187 bool ChromeContentBrowserClientExtensionsPart::ShouldLockToOrigin(
 188     content::BrowserContext* browser_context,
 189     const GURL& effective_site_url) {
 190   // https://crbug.com/160576 workaround: Origin lock to the chrome-extension://
 191   // scheme for a hosted app would kill processes on legitimate requests for the
 192   // app's cookies.
 193   if (effective_site_url.SchemeIs(extensions::kExtensionScheme)) {
 194     const Extension* extension =
 195         ExtensionRegistry::Get(browser_context)
 196             ->enabled_extensions()
 197             .GetExtensionOrAppByURL(effective_site_url);
 198     if (extension && extension->is_hosted_app())
 199       return false;
 200   }
 201   return true;
 202 }
 203
 204 // static
 205 bool ChromeContentBrowserClientExtensionsPart::CanCommitURL(
 206     content::RenderProcessHost* process_host, const GURL& url) {
 207   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 208
 209   // We need to let most extension URLs commit in any process, since this can
 210   // be allowed due to web_accessible_resources.  Most hosted app URLs may also
 211   // load in any process (e.g., in an iframe).  However, the Chrome Web Store
 212   // cannot be loaded in iframes and should never be requested outside its
 213   // process.
 214   ExtensionRegistry* registry =
 215       ExtensionRegistry::Get(process_host->GetBrowserContext());
 216   if (!registry)
 217     return true;
 218
 219   const Extension* new_extension =
 220       registry->enabled_extensions().GetExtensionOrAppByURL(url);
 221   if (new_extension && new_extension->is_hosted_app() &&
 222       new_extension->id() == kWebStoreAppId &&
 223       !ProcessMap::Get(process_host->GetBrowserContext())
 224            ->Contains(new_extension->id(), process_host->GetID())) {
 225     return false;
 226   }
 227   return true;
 228 }
 229
 230 bool ChromeContentBrowserClientExtensionsPart::IsIllegalOrigin(
 231     content::ResourceContext* resource_context,
 232     int child_process_id,
 233     const GURL& origin) {
 234   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 235
 236   // Consider non-extension URLs safe; they will be checked elsewhere.
 237   if (!origin.SchemeIs(kExtensionScheme))
 238     return false;
 239
 240   // If there is no extension installed for the URL, it couldn't have committed.
 241   // (If the extension was recently uninstalled, the tab would have closed.)
 242   ProfileIOData* io_data = ProfileIOData::FromResourceContext(resource_context);
 243   InfoMap* extension_info_map = io_data->GetExtensionInfoMap();
 244   const Extension* extension =
 245       extension_info_map->extensions().GetExtensionOrAppByURL(origin);
 246   if (!extension)
 247     return true;
 248
 249   // Check for platform app origins.  These can only be committed by the app
 250   // itself, or by one if its guests if there are accessible_resources.
 251   const ProcessMap& process_map = extension_info_map->process_map();
 252   if (extension->is_platform_app() &&
 253       !process_map.Contains(extension->id(), child_process_id)) {
 254     // This is a platform app origin not in the app's own process.  If there are
 255     // no accessible resources, this is illegal.
 256     if (!extension->GetManifestData(manifest_keys::kWebviewAccessibleResources))
 257       return true;
 258
 259     // If there are accessible resources, the origin is only legal if the given
 260     // process is a guest of the app.
 261     std::string owner_extension_id;
 262     int owner_process_id;
 263     WebViewRendererState::GetInstance()->GetOwnerInfo(
 264         child_process_id, &owner_process_id, &owner_extension_id);
 265     const Extension* owner_extension =
 266         extension_info_map->extensions().GetByID(owner_extension_id);
 267     return !owner_extension || owner_extension != extension;
 268   }
 269
 270   // With only the origin and not the full URL, we don't have enough information
 271   // to validate hosted apps or web_accessible_resources in normal extensions.
 272   // Assume they're legal.
 273   return false;
 274 }
 275
 276 // static
 277 bool ChromeContentBrowserClientExtensionsPart::IsSuitableHost(
 278     Profile* profile,
 279     content::RenderProcessHost* process_host,
 280     const GURL& site_url) {
 281   DCHECK(profile);
 282
 283   ExtensionRegistry* registry = ExtensionRegistry::Get(profile);
 284   ProcessMap* process_map = ProcessMap::Get(profile);
 285
 286   // These may be NULL during tests. In that case, just assume any site can
 287   // share any host.
 288   if (!registry || !process_map)
 289     return true;
 290
 291   // Otherwise, just make sure the process privilege matches the privilege
 292   // required by the site.
 293   RenderProcessHostPrivilege privilege_required =
 294       GetPrivilegeRequiredByUrl(site_url, registry);
 295   return GetProcessPrivilege(process_host, process_map, registry) ==
 296          privilege_required;
 297 }
 298
 299 // static
 300 bool
 301 ChromeContentBrowserClientExtensionsPart::ShouldTryToUseExistingProcessHost(
 302     Profile* profile, const GURL& url) {
 303   // This function is trying to limit the amount of processes used by extensions
 304   // with background pages. It uses a globally set percentage of processes to
 305   // run such extensions and if the limit is exceeded, it returns true, to
 306   // indicate to the content module to group extensions together.
 307   ExtensionRegistry* registry =
 308       profile ? ExtensionRegistry::Get(profile) : NULL;
 309   if (!registry)
 310     return false;
 311
 312   // We have to have a valid extension with background page to proceed.
 313   const Extension* extension =
 314       registry->enabled_extensions().GetExtensionOrAppByURL(url);
 315   if (!extension)
 316     return false;
 317   if (!BackgroundInfo::HasBackgroundPage(extension))
 318     return false;
 319
 320   std::set<int> process_ids;
 321   size_t max_process_count =
 322       content::RenderProcessHost::GetMaxRendererProcessCount();
 323
 324   // Go through all profiles to ensure we have total count of extension
 325   // processes containing background pages, otherwise one profile can
 326   // starve the other.
 327   std::vector<Profile*> profiles = g_browser_process->profile_manager()->
 328       GetLoadedProfiles();
 329   for (size_t i = 0; i < profiles.size(); ++i) {
 330     ProcessManager* epm = ProcessManager::Get(profiles[i]);
 331     for (ExtensionHost* host : epm->background_hosts())
 332       process_ids.insert(host->render_process_host()->GetID());
 333   }
 334
 335   return (process_ids.size() >
 336           (max_process_count * chrome::kMaxShareOfExtensionProcesses));
 337 }
 338
 339 // static
 340 bool ChromeContentBrowserClientExtensionsPart::
 341     ShouldSwapBrowsingInstancesForNavigation(SiteInstance* site_instance,
 342                                              const GURL& current_url,
 343                                              const GURL& new_url) {
 344   // If we don't have an ExtensionRegistry, then rely on the SiteInstance logic
 345   // in RenderFrameHostManager to decide when to swap.
 346   ExtensionRegistry* registry =
 347       ExtensionRegistry::Get(site_instance->GetBrowserContext());
 348   if (!registry)
 349     return false;
 350
 351   // We must use a new BrowsingInstance (forcing a process swap and disabling
 352   // scripting by existing tabs) if one of the URLs is an extension and the
 353   // other is not the exact same extension.
 354   //
 355   // We ignore hosted apps here so that other tabs in their BrowsingInstance can
 356   // use postMessage with them.  (The exception is the Chrome Web Store, which
 357   // is a hosted app that requires its own BrowsingInstance.)  Navigations
 358   // to/from a hosted app will still trigger a SiteInstance swap in
 359   // RenderFrameHostManager.
 360   const Extension* current_extension =
 361       registry->enabled_extensions().GetExtensionOrAppByURL(current_url);
 362   if (current_extension && current_extension->is_hosted_app() &&
 363       current_extension->id() != kWebStoreAppId)
 364     current_extension = NULL;
 365
 366   const Extension* new_extension =
 367       registry->enabled_extensions().GetExtensionOrAppByURL(new_url);
 368   if (new_extension && new_extension->is_hosted_app() &&
 369       new_extension->id() != kWebStoreAppId)
 370     new_extension = NULL;
 371
 372   // First do a process check.  We should force a BrowsingInstance swap if the
 373   // current process doesn't know about new_extension, even if current_extension
 374   // is somehow the same as new_extension.
 375   ProcessMap* process_map = ProcessMap::Get(site_instance->GetBrowserContext());
 376   if (new_extension &&
 377       site_instance->HasProcess() &&
 378       !process_map->Contains(
 379           new_extension->id(), site_instance->GetProcess()->GetID()))
 380     return true;
 381
 382   // Otherwise, swap BrowsingInstances if current_extension and new_extension
 383   // differ.
 384   return current_extension != new_extension;
 385 }
 386
 387 // static
 388 bool ChromeContentBrowserClientExtensionsPart::ShouldSwapProcessesForRedirect(
 389     content::ResourceContext* resource_context,
 390     const GURL& current_url,
 391     const GURL& new_url) {
 392   ProfileIOData* io_data = ProfileIOData::FromResourceContext(resource_context);
 393   return CrossesExtensionProcessBoundary(
 394       io_data->GetExtensionInfoMap()->extensions(),
 395       current_url, new_url, false);
 396 }
 397
 398 // static
 399 bool ChromeContentBrowserClientExtensionsPart::AllowServiceWorker(
 400     const GURL& scope,
 401     const GURL& first_party_url,
 402     content::ResourceContext* context,
 403     int render_process_id,
 404     int render_frame_id) {
 405   // We only care about extension urls.
 406   // TODO(devlin): Also address chrome-extension-resource.
 407   if (!first_party_url.SchemeIs(kExtensionScheme))
 408     return true;
 409
 410   ProfileIOData* io_data = ProfileIOData::FromResourceContext(context);
 411   InfoMap* extension_info_map = io_data->GetExtensionInfoMap();
 412   const Extension* extension =
 413       extension_info_map->extensions().GetExtensionOrAppByURL(first_party_url);
 414   // Don't allow a service worker for an extension url with no extension (this
 415   // could happen in the case of, e.g., an unloaded extension).
 416   return extension != nullptr;
 417 }
 418
 419 // static
 420 bool ChromeContentBrowserClientExtensionsPart::ShouldAllowOpenURL(
 421     content::SiteInstance* site_instance,
 422     const GURL& from_url,
 423     const GURL& to_url,
 424     bool* result) {
 425   DCHECK(result);
 426
 427   // Do not allow pages from the web or other extensions navigate to
 428   // non-web-accessible extension resources.
 429   if (to_url.SchemeIs(kExtensionScheme) &&
 430       (from_url.SchemeIsHTTPOrHTTPS() || from_url.SchemeIs(kExtensionScheme))) {
 431     Profile* profile = Profile::FromBrowserContext(
 432         site_instance->GetProcess()->GetBrowserContext());
 433     ExtensionRegistry* registry = ExtensionRegistry::Get(profile);
 434     if (!registry) {
 435       *result = true;
 436       return true;
 437     }
 438     const Extension* extension =
 439         registry->enabled_extensions().GetExtensionOrAppByURL(to_url);
 440     if (!extension) {
 441       *result = true;
 442       return true;
 443     }
 444     const Extension* from_extension =
 445         registry->enabled_extensions().GetExtensionOrAppByURL(
 446             site_instance->GetSiteURL());
 447     if (from_extension && from_extension->id() == extension->id()) {
 448       *result = true;
 449       return true;
 450     }
 451
 452     if (!WebAccessibleResourcesInfo::IsResourceWebAccessible(
 453             extension, to_url.path())) {
 454       *result = false;
 455       return true;
 456     }
 457   }
 458   return false;
 459 }
 460
 461 void ChromeContentBrowserClientExtensionsPart::RenderProcessWillLaunch(
 462     content::RenderProcessHost* host) {
 463   int id = host->GetID();
 464   Profile* profile = Profile::FromBrowserContext(host->GetBrowserContext());
 465
 466   host->AddFilter(new ChromeExtensionMessageFilter(id, profile));
 467   host->AddFilter(new ExtensionMessageFilter(id, profile));
 468   host->AddFilter(new IOThreadExtensionMessageFilter(id, profile));
 469   host->AddFilter(new ExtensionsGuestViewMessageFilter(id, profile));
 470   extension_web_request_api_helpers::SendExtensionWebRequestStatusToHost(host);
 471 }
 472
 473 void ChromeContentBrowserClientExtensionsPart::SiteInstanceGotProcess(
 474     SiteInstance* site_instance) {
 475   BrowserContext* context = site_instance->GetProcess()->GetBrowserContext();
 476   ExtensionRegistry* registry = ExtensionRegistry::Get(context);
 477   if (!registry)
 478     return;
 479
 480   const Extension* extension =
 481       registry->enabled_extensions().GetExtensionOrAppByURL(
 482           site_instance->GetSiteURL());
 483   if (!extension)
 484     return;
 485
 486   ProcessMap::Get(context)->Insert(extension->id(),
 487                                    site_instance->GetProcess()->GetID(),
 488                                    site_instance->GetId());
 489
 490   BrowserThread::PostTask(
 491       BrowserThread::IO, FROM_HERE,
 492       base::Bind(&InfoMap::RegisterExtensionProcess,
 493                  ExtensionSystem::Get(context)->info_map(), extension->id(),
 494                  site_instance->GetProcess()->GetID(), site_instance->GetId()));
 495 }
 496
 497 void ChromeContentBrowserClientExtensionsPart::SiteInstanceDeleting(
 498     SiteInstance* site_instance) {
 499   BrowserContext* context = site_instance->GetBrowserContext();
 500   ExtensionRegistry* registry = ExtensionRegistry::Get(context);
 501   if (!registry)
 502     return;
 503
 504   const Extension* extension =
 505       registry->enabled_extensions().GetExtensionOrAppByURL(
 506           site_instance->GetSiteURL());
 507   if (!extension)
 508     return;
 509
 510   ProcessMap::Get(context)->Remove(extension->id(),
 511                                    site_instance->GetProcess()->GetID(),
 512                                    site_instance->GetId());
 513
 514   BrowserThread::PostTask(
 515       BrowserThread::IO, FROM_HERE,
 516       base::Bind(&InfoMap::UnregisterExtensionProcess,
 517                  ExtensionSystem::Get(context)->info_map(), extension->id(),
 518                  site_instance->GetProcess()->GetID(), site_instance->GetId()));
 519 }
 520
 521 void ChromeContentBrowserClientExtensionsPart::OverrideWebkitPrefs(
 522     RenderViewHost* rvh,
 523     WebPreferences* web_prefs) {
 524   const ExtensionRegistry* registry =
 525       ExtensionRegistry::Get(rvh->GetProcess()->GetBrowserContext());
 526   if (!registry)
 527     return;
 528
 529   // Note: it's not possible for kExtensionsScheme to change during the lifetime
 530   // of the process.
 531   //
 532   // Ensure that we are only granting extension preferences to URLs with
 533   // the correct scheme. Without this check, chrome-guest:// schemes used by
 534   // webview tags as well as hosts that happen to match the id of an
 535   // installed extension would get the wrong preferences.
 536   const GURL& site_url = rvh->GetSiteInstance()->GetSiteURL();
 537   if (!site_url.SchemeIs(kExtensionScheme))
 538     return;
 539
 540   WebContents* web_contents = WebContents::FromRenderViewHost(rvh);
 541   ViewType view_type = GetViewType(web_contents);
 542   const Extension* extension =
 543       registry->enabled_extensions().GetByID(site_url.host());
 544   extension_webkit_preferences::SetPreferences(extension, view_type, web_prefs);
 545 }
 546
 547 void ChromeContentBrowserClientExtensionsPart::BrowserURLHandlerCreated(
 548     BrowserURLHandler* handler) {
 549   handler->AddHandlerPair(&ExtensionWebUI::HandleChromeURLOverride,
 550                           BrowserURLHandler::null_handler());
 551   handler->AddHandlerPair(BrowserURLHandler::null_handler(),
 552                           &ExtensionWebUI::HandleChromeURLOverrideReverse);
 553 }
 554
 555 void ChromeContentBrowserClientExtensionsPart::
 556     GetAdditionalAllowedSchemesForFileSystem(
 557         std::vector<std::string>* additional_allowed_schemes) {
 558   additional_allowed_schemes->push_back(kExtensionScheme);
 559 }
 560
 561 void ChromeContentBrowserClientExtensionsPart::GetURLRequestAutoMountHandlers(
 562     std::vector<storage::URLRequestAutoMountHandler>* handlers) {
 563   handlers->push_back(
 564       base::Bind(MediaFileSystemBackend::AttemptAutoMountForURLRequest));
 565 }
 566
 567 void ChromeContentBrowserClientExtensionsPart::GetAdditionalFileSystemBackends(
 568     content::BrowserContext* browser_context,
 569     const base::FilePath& storage_partition_path,
 570     ScopedVector<storage::FileSystemBackend>* additional_backends) {
 571   base::SequencedWorkerPool* pool = content::BrowserThread::GetBlockingPool();
 572   additional_backends->push_back(new MediaFileSystemBackend(
 573       storage_partition_path,
 574       pool->GetSequencedTaskRunner(
 575                 pool->GetNamedSequenceToken(
 576                     MediaFileSystemBackend::kMediaTaskRunnerName)).get()));
 577
 578   additional_backends->push_back(new sync_file_system::SyncFileSystemBackend(
 579       Profile::FromBrowserContext(browser_context)));
 580 }
 581
 582 void ChromeContentBrowserClientExtensionsPart::
 583     AppendExtraRendererCommandLineSwitches(base::CommandLine* command_line,
 584                                            content::RenderProcessHost* process,
 585                                            Profile* profile) {
 586   if (!process)
 587     return;
 588   DCHECK(profile);
 589   if (ProcessMap::Get(profile)->Contains(process->GetID())) {
 590     command_line->AppendSwitch(switches::kExtensionProcess);
 591 #if defined(ENABLE_WEBRTC)
 592     command_line->AppendSwitch(::switches::kEnableWebRtcHWH264Encoding);
 593 #endif
 594     if (base::CommandLine::ForCurrentProcess()->HasSwitch(
 595             switches::kEnableMojoSerialService)) {
 596       command_line->AppendSwitch(switches::kEnableMojoSerialService);
 597     }
 598   }
 599 }
 600
 601 }  // namespace extensions