path: root/chrome/browser/extensions/extension_service.cc

// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/extensions/extension_service.h"

#include <algorithm>
#include <set>

#include "base/basictypes.h"
#include "base/command_line.h"
#include "base/file_util.h"
#include "base/metrics/histogram.h"
#include "base/stl_util-inl.h"
#include "base/string16.h"
#include "base/string_number_conversions.h"
#include "base/string_util.h"
#include "base/stringprintf.h"
#include "base/threading/thread_restrictions.h"
#include "base/time.h"
#include "base/utf_string_conversions.h"
#include "base/values.h"
#include "base/version.h"
#include "chrome/browser/browser_process.h"
#include "chrome/browser/debugger/devtools_manager.h"
#include "chrome/browser/extensions/crx_installer.h"
#include "chrome/browser/extensions/default_apps.h"
#include "chrome/browser/extensions/extension_accessibility_api.h"
#include "chrome/browser/extensions/extension_bookmarks_module.h"
#include "chrome/browser/extensions/extension_browser_event_router.h"
#include "chrome/browser/extensions/extension_cookies_api.h"
#include "chrome/browser/extensions/extension_data_deleter.h"
#include "chrome/browser/extensions/extension_error_reporter.h"
#include "chrome/browser/extensions/extension_history_api.h"
#include "chrome/browser/extensions/extension_host.h"
#include "chrome/browser/extensions/extension_management_api.h"
#include "chrome/browser/extensions/extension_process_manager.h"
#include "chrome/browser/extensions/extension_processes_api.h"
#include "chrome/browser/extensions/extension_special_storage_policy.h"
#include "chrome/browser/extensions/extension_updater.h"
#include "chrome/browser/extensions/extension_web_ui.h"
#include "chrome/browser/extensions/extension_webnavigation_api.h"
#include "chrome/browser/extensions/external_extension_provider_impl.h"
#include "chrome/browser/extensions/external_extension_provider_interface.h"
#include "chrome/browser/net/chrome_url_request_context.h"
#include "chrome/browser/prefs/pref_service.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/search_engines/template_url_model.h"
#include "chrome/browser/themes/browser_theme_provider.h"
#include "chrome/browser/ui/webui/shown_sections_handler.h"
#include "chrome/common/child_process_logging.h"
#include "chrome/common/chrome_switches.h"
#include "chrome/common/extensions/extension.h"
#include "chrome/common/extensions/extension_constants.h"
#include "chrome/common/extensions/extension_error_utils.h"
#include "chrome/common/extensions/extension_file_util.h"
#include "chrome/common/extensions/extension_l10n_util.h"
#include "chrome/common/extensions/extension_resource.h"
#include "chrome/common/json_value_serializer.h"
#include "chrome/common/notification_service.h"
#include "chrome/common/notification_type.h"
#include "chrome/common/pref_names.h"
#include "chrome/common/url_constants.h"
#include "content/browser/browser_thread.h"
#include "googleurl/src/gurl.h"
#include "net/base/registry_controlled_domain.h"
#include "webkit/database/database_tracker.h"
#include "webkit/database/database_util.h"

using base::Time;

namespace errors = extension_manifest_errors;

namespace {

#if defined(OS_LINUX)
static const int kOmniboxIconPaddingLeft = 2;
static const int kOmniboxIconPaddingRight = 2;
#elif defined(OS_MACOSX)
static const int kOmniboxIconPaddingLeft = 0;
static const int kOmniboxIconPaddingRight = 2;
#else
static const int kOmniboxIconPaddingLeft = 0;
static const int kOmniboxIconPaddingRight = 0;
#endif

// The following enumeration is used in histograms matching
// Extensions.ManifestReload* .  Values may be added, as long
// as existing values are not changed.
enum ManifestReloadReason {
  NOT_NEEDED = 0,  // Reload not needed.
  UNPACKED_DIR,  // Unpacked directory
  NEEDS_RELOCALIZATION,  // The local has changed since we read this extension.
  NUM_MANIFEST_RELOAD_REASONS
};

ManifestReloadReason ShouldReloadExtensionManifest(const ExtensionInfo& info) {
  // Always reload manifests of unpacked extensions, because they can change
  // on disk independent of the manifest in our prefs.
  if (info.extension_location == Extension::LOAD)
    return UNPACKED_DIR;

  // Reload the manifest if it needs to be relocalized.
  if (extension_l10n_util::ShouldRelocalizeManifest(info))
    return NEEDS_RELOCALIZATION;

  return NOT_NEEDED;
}

}  // namespace


ExtensionService::ExtensionRuntimeData::ExtensionRuntimeData()
    : background_page_ready(false),
      being_upgraded(false) {
}

ExtensionService::ExtensionRuntimeData::~ExtensionRuntimeData() {
}

// ExtensionService.

const char* ExtensionService::kInstallDirectoryName = "Extensions";
const char* ExtensionService::kCurrentVersionFileName = "Current Version";

// Implements IO for the ExtensionService.

class ExtensionServiceBackend
    : public base::RefCountedThreadSafe<ExtensionServiceBackend> {
 public:
  // |install_directory| is a path where to look for extensions to load.
  explicit ExtensionServiceBackend(const FilePath& install_directory);

  // Loads a single extension from |path| where |path| is the top directory of
  // a specific extension where its manifest file lives.
  // Errors are reported through ExtensionErrorReporter. On success,
  // AddExtension() is called.
  // TODO(erikkay): It might be useful to be able to load a packed extension
  // (presumably into memory) without installing it.
  void LoadSingleExtension(const FilePath &path,
                           scoped_refptr<ExtensionService> frontend);

 private:
  friend class base::RefCountedThreadSafe<ExtensionServiceBackend>;

  virtual ~ExtensionServiceBackend();

  // Finish installing the extension in |crx_path| after it has been unpacked to
  // |unpacked_path|.  If |expected_id| is not empty, it's verified against the
  // extension's manifest before installation. If |silent| is true, there will
  // be no install confirmation dialog. |from_gallery| indicates whether the
  // crx was installed from our gallery, which results in different UI.
  //
  // Note: We take ownership of |extension|.
  void OnExtensionUnpacked(const FilePath& crx_path,
                           const FilePath& unpacked_path,
                           const Extension* extension,
                           const std::string expected_id);

  // Notify the frontend that there was an error loading an extension.
  void ReportExtensionLoadError(const FilePath& extension_path,
                                const std::string& error);

  // This is a naked pointer which is set by each entry point.
  // The entry point is responsible for ensuring lifetime.
  ExtensionService* frontend_;

  // The top-level extensions directory being installed to.
  FilePath install_directory_;

  // Whether errors result in noisy alerts.
  bool alert_on_error_;

  DISALLOW_COPY_AND_ASSIGN(ExtensionServiceBackend);
};

ExtensionServiceBackend::ExtensionServiceBackend(
    const FilePath& install_directory)
        : frontend_(NULL),
          install_directory_(install_directory),
          alert_on_error_(false) {
}

ExtensionServiceBackend::~ExtensionServiceBackend() {
}

void ExtensionServiceBackend::LoadSingleExtension(
    const FilePath& path_in, scoped_refptr<ExtensionService> frontend) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));

  frontend_ = frontend;

  // Explicit UI loads are always noisy.
  alert_on_error_ = true;

  FilePath extension_path = path_in;
  file_util::AbsolutePath(&extension_path);

  std::string error;
  scoped_refptr<const Extension> extension(extension_file_util::LoadExtension(
      extension_path,
      Extension::LOAD,
      false,  // Don't require id
      Extension::ShouldDoStrictErrorChecking(Extension::LOAD),
      &error));

  if (!extension) {
    ReportExtensionLoadError(extension_path, error);
    return;
  }

  // Report this as an installed extension so that it gets remembered in the
  // prefs.
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      NewRunnableMethod(frontend_,
                        &ExtensionService::OnExtensionInstalled,
                        extension));
}

void ExtensionServiceBackend::ReportExtensionLoadError(
    const FilePath& extension_path, const std::string &error) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      NewRunnableMethod(
          frontend_,
          &ExtensionService::ReportExtensionLoadError, extension_path,
          error, NotificationType::EXTENSION_INSTALL_ERROR, alert_on_error_));
}

void ExtensionService::CheckExternalUninstall(const std::string& id) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  // Check if the providers know about this extension.
  ProviderCollection::const_iterator i;
  for (i = external_extension_providers_.begin();
       i != external_extension_providers_.end(); ++i) {
    DCHECK(i->get()->IsReady());
    if (i->get()->HasExtension(id))
      return;  // Yup, known extension, don't uninstall.
  }

  // This is an external extension that we don't have registered.  Uninstall.
  UninstallExtension(id, true);
}

void ExtensionService::ClearProvidersForTesting() {
  external_extension_providers_.clear();
}

void ExtensionService::AddProviderForTesting(
    ExternalExtensionProviderInterface* test_provider) {
  CHECK(test_provider);
  external_extension_providers_.push_back(
      linked_ptr<ExternalExtensionProviderInterface>(test_provider));
}

void ExtensionService::OnExternalExtensionUpdateUrlFound(
    const std::string& id,
    const GURL& update_url,
    Extension::Location location) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  CHECK(Extension::IdIsValid(id));

  if (GetExtensionById(id, true)) {
    // Already installed.  Do not change the update URL that the extension set.
    return;
  }
  AddPendingExtensionFromExternalUpdateUrl(id, update_url, location);
  external_extension_url_added_ |= true;
}

bool ExtensionService::IsDownloadFromGallery(const GURL& download_url,
                                             const GURL& referrer_url) {
  // Special-case the themes mini-gallery.
  // TODO(erikkay) When that gallery goes away, remove this code.
  if (IsDownloadFromMiniGallery(download_url) &&
      StartsWithASCII(referrer_url.spec(),
                      extension_urls::kMiniGalleryBrowsePrefix, false)) {
    return true;
  }

  const Extension* download_extension = GetExtensionByWebExtent(download_url);
  const Extension* referrer_extension = GetExtensionByWebExtent(referrer_url);
  const Extension* webstore_app = GetWebStoreApp();

  bool referrer_valid = (referrer_extension == webstore_app);
  bool download_valid = (download_extension == webstore_app);

  // If the command-line gallery URL is set, then be a bit more lenient.
  GURL store_url =
      GURL(CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
           switches::kAppsGalleryURL));
  if (!store_url.is_empty()) {
    std::string store_tld =
        net::RegistryControlledDomainService::GetDomainAndRegistry(store_url);
    if (!referrer_valid) {
      std::string referrer_tld =
          net::RegistryControlledDomainService::GetDomainAndRegistry(
              referrer_url);
      // The referrer gets stripped when transitioning from https to http,
      // or when hitting an unknown test cert and that commonly happens in
      // testing environments.  Given this, we allow an empty referrer when
      // the command-line flag is set.
      // Otherwise, the TLD must match the TLD of the command-line url.
      referrer_valid = referrer_url.is_empty() || (referrer_tld == store_tld);
    }

    if (!download_valid) {
      std::string download_tld =
          net::RegistryControlledDomainService::GetDomainAndRegistry(
              GURL(download_url));

      // Otherwise, the TLD must match the TLD of the command-line url.
      download_valid = (download_tld == store_tld);
    }
  }

  return (referrer_valid && download_valid);
}

bool ExtensionService::IsDownloadFromMiniGallery(const GURL& download_url) {
  return StartsWithASCII(download_url.spec(),
                         extension_urls::kMiniGalleryDownloadPrefix,
                         false);  // case_sensitive
}

bool ExtensionService::IsInstalledApp(const GURL& url) {
  // Check for hosted app.
  if (GetExtensionByWebExtent(url) != NULL)
    return true;

  // Check for packaged app.
  const Extension* extension = GetExtensionByURL(url);
  return extension != NULL && extension->is_app();
}

// static
bool ExtensionService::UninstallExtensionHelper(
    ExtensionService* extensions_service,
    const std::string& extension_id) {

  // We can't call UninstallExtension with an invalid extension ID, so check it
  // first.
  if (extensions_service->GetExtensionById(extension_id, true) ||
      extensions_service->GetTerminatedExtension(extension_id)) {
    extensions_service->UninstallExtension(extension_id, false);
  } else {
    LOG(WARNING) << "Attempted uninstallation of non-existent extension with "
      << "id: " << extension_id;
    return false;
  }

  return true;
}

ExtensionService::ExtensionService(Profile* profile,
                                   const CommandLine* command_line,
                                   const FilePath& install_directory,
                                   ExtensionPrefs* extension_prefs,
                                   bool autoupdate_enabled)
    : profile_(profile),
      extension_prefs_(extension_prefs),
      install_directory_(install_directory),
      extensions_enabled_(true),
      show_extensions_prompts_(true),
      ready_(false),
      ALLOW_THIS_IN_INITIALIZER_LIST(toolbar_model_(this)),
      default_apps_(profile->GetPrefs(),
                    g_browser_process->GetApplicationLocale()),
      event_routers_initialized_(false) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  // Figure out if extension installation should be enabled.
  if (command_line->HasSwitch(switches::kDisableExtensions)) {
    extensions_enabled_ = false;
  } else if (profile->GetPrefs()->GetBoolean(prefs::kDisableExtensions)) {
    extensions_enabled_ = false;
  }

  registrar_.Add(this, NotificationType::EXTENSION_PROCESS_TERMINATED,
                 NotificationService::AllSources());
  pref_change_registrar_.Init(profile->GetPrefs());
  pref_change_registrar_.Add(prefs::kExtensionInstallAllowList, this);
  pref_change_registrar_.Add(prefs::kExtensionInstallDenyList, this);

  // Set up the ExtensionUpdater
  if (autoupdate_enabled) {
    int update_frequency = kDefaultUpdateFrequencySeconds;
    if (command_line->HasSwitch(switches::kExtensionsUpdateFrequency)) {
      base::StringToInt(command_line->GetSwitchValueASCII(
          switches::kExtensionsUpdateFrequency),
          &update_frequency);
    }
    updater_ = new ExtensionUpdater(this,
                                    profile->GetPrefs(),
                                    update_frequency);
  }

  backend_ = new ExtensionServiceBackend(install_directory_);

  ExternalExtensionProviderImpl::CreateExternalProviders(
      this, profile_, &external_extension_providers_);

  // Use monochrome icons for Omnibox icons.
  omnibox_popup_icon_manager_.set_monochrome(true);
  omnibox_icon_manager_.set_monochrome(true);
  omnibox_icon_manager_.set_padding(gfx::Insets(0, kOmniboxIconPaddingLeft,
                                                0, kOmniboxIconPaddingRight));
}

const ExtensionList* ExtensionService::extensions() const {
  return &extensions_;
}

const ExtensionList* ExtensionService::disabled_extensions() const {
  return &disabled_extensions_;
}

const ExtensionList* ExtensionService::terminated_extensions() const {
  return &terminated_extensions_;
}

const PendingExtensionMap& ExtensionService::pending_extensions() const {
  return pending_extensions_;
}

bool ExtensionService::HasInstalledExtensions() {
  return !(extensions_.empty() && disabled_extensions_.empty());
}

ExtensionService::~ExtensionService() {
  DCHECK(!profile_);  // Profile should have told us it's going away.
  UnloadAllExtensions();

  ProviderCollection::const_iterator i;
  for (i = external_extension_providers_.begin();
       i != external_extension_providers_.end(); ++i) {
    ExternalExtensionProviderInterface* provider = i->get();
    provider->ServiceShutdown();
  }
}

void ExtensionService::InitEventRouters() {
  if (event_routers_initialized_)
    return;

  ExtensionHistoryEventRouter::GetInstance()->ObserveProfile(profile_);
  ExtensionAccessibilityEventRouter::GetInstance()->ObserveProfile(profile_);
  browser_event_router_.reset(new ExtensionBrowserEventRouter(profile_));
  browser_event_router_->Init();
  ExtensionBookmarkEventRouter::GetInstance()->Observe(
      profile_->GetBookmarkModel());
  ExtensionCookiesEventRouter::GetInstance()->Init();
  ExtensionManagementEventRouter::GetInstance()->Init();
  ExtensionProcessesEventRouter::GetInstance()->ObserveProfile(profile_);
  ExtensionWebNavigationEventRouter::GetInstance()->Init();
  event_routers_initialized_ = true;
}

const Extension* ExtensionService::GetExtensionById(const std::string& id,
                                                     bool include_disabled) {
  return GetExtensionByIdInternal(id, true, include_disabled);
}

void ExtensionService::Init() {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  DCHECK(!ready_);  // Can't redo init.
  DCHECK_EQ(extensions_.size(), 0u);

  // Hack: we need to ensure the ResourceDispatcherHost is ready before we load
  // the first extension, because its members listen for loaded notifications.
  g_browser_process->resource_dispatcher_host();

  LoadAllExtensions();

  // TODO(erikkay) this should probably be deferred to a future point
  // rather than running immediately at startup.
  CheckForExternalUpdates();

  // TODO(erikkay) this should probably be deferred as well.
  GarbageCollectExtensions();
}

void ExtensionService::UpdateExtension(const std::string& id,
                                       const FilePath& extension_path,
                                       const GURL& download_url) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  PendingExtensionMap::const_iterator it = pending_extensions_.find(id);
  bool is_pending_extension = (it != pending_extensions_.end());

  const Extension* extension = GetExtensionByIdInternal(id, true, true);
  if (!is_pending_extension && !extension) {
    LOG(WARNING) << "Will not update extension " << id
                 << " because it is not installed or pending";
    // Delete extension_path since we're not creating a CrxInstaller
    // that would do it for us.
    BrowserThread::PostTask(
        BrowserThread::FILE, FROM_HERE,
        NewRunnableFunction(
            extension_file_util::DeleteFile, extension_path, false));
    return;
  }

  // We want a silent install only for non-pending extensions and
  // pending extensions that have install_silently set.
  ExtensionInstallUI* client =
      (!is_pending_extension || it->second.install_silently()) ?
      NULL : new ExtensionInstallUI(profile_);

  scoped_refptr<CrxInstaller> installer(
      new CrxInstaller(this,  // frontend
                       client));
  installer->set_expected_id(id);
  if (is_pending_extension)
    installer->set_install_source(it->second.install_source());
  else if (extension)
    installer->set_install_source(extension->location());
  installer->set_delete_source(true);
  installer->set_original_url(download_url);
  installer->InstallCrx(extension_path);
}

void ExtensionService::AddPendingExtensionFromSync(
    const std::string& id, const GURL& update_url,
    PendingExtensionInfo::ShouldAllowInstallPredicate should_allow_install,
    bool install_silently, bool enable_on_install,
    bool enable_incognito_on_install) {
  if (GetExtensionByIdInternal(id, true, true)) {
    LOG(DFATAL) << "Trying to add pending extension " << id
                << " which already exists";
    return;
  }

  AddPendingExtensionInternal(id, update_url, should_allow_install, true,
                              install_silently, enable_on_install,
                              enable_incognito_on_install,
                              Extension::INTERNAL);
}

namespace {

bool AlwaysInstall(const Extension& extension) {
  return true;
}

}  // namespace

void ExtensionService::AddPendingExtensionFromExternalUpdateUrl(
    const std::string& id, const GURL& update_url,
    Extension::Location location) {
  const bool kIsFromSync = false;
  const bool kInstallSilently = true;
  const bool kEnableOnInstall = true;
  const bool kEnableIncognitoOnInstall = false;
  if (extension_prefs_->IsExtensionKilled(id))
    return;

  if (GetExtensionByIdInternal(id, true, true)) {
    LOG(DFATAL) << "Trying to add extension " << id
                << " by external update, but it is already installed.";
    return;
  }

  AddPendingExtensionInternal(id, update_url, &AlwaysInstall,
                              kIsFromSync, kInstallSilently,
                              kEnableOnInstall, kEnableIncognitoOnInstall,
                              location);
}

namespace {

bool IsApp(const Extension& extension) {
  return extension.is_app();
}

}  // namespace

// TODO(akalin): Change DefaultAppList to DefaultExtensionList and
// remove the IsApp() check.

void ExtensionService::AddPendingExtensionFromDefaultAppList(
    const std::string& id) {
  const bool kIsFromSync = false;
  const bool kInstallSilently = true;
  const bool kEnableOnInstall = true;
  const bool kEnableIncognitoOnInstall = true;

  // This can legitimately happen if the user manually installed one of the
  // default apps before this code ran.
  if (GetExtensionByIdInternal(id, true, true))
    return;

  AddPendingExtensionInternal(id, GURL(), &IsApp,
                              kIsFromSync, kInstallSilently,
                              kEnableOnInstall, kEnableIncognitoOnInstall,
                              Extension::INTERNAL);
}

void ExtensionService::AddPendingExtensionInternal(
    const std::string& id, const GURL& update_url,
    PendingExtensionInfo::ShouldAllowInstallPredicate should_allow_install,
    bool is_from_sync, bool install_silently,
    bool enable_on_install, bool enable_incognito_on_install,
    Extension::Location install_source) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  // If a non-sync update is pending, a sync request should not
  // overwrite it.  This is important for external extensions.
  // If an external extension download is pending, and the user has
  // the extension in their sync profile, the install should set the
  // type to be external.  An external extension should not be
  // rejected if it fails the safty checks for a syncable extension.
  // TODO(skerner): Work out other potential overlapping conditions.
  // (crbug.com/61000)
  PendingExtensionMap::iterator it = pending_extensions_.find(id);
  if (it != pending_extensions_.end()) {
    VLOG(1) << "Extension id " << id
            << " was entered for update more than once."
            << "  old is_from_sync = " << it->second.is_from_sync()
            << "  new is_from_sync = " << is_from_sync;
    if (!it->second.is_from_sync() && is_from_sync)
      return;
  }

  pending_extensions_[id] =
      PendingExtensionInfo(update_url, should_allow_install,
                           is_from_sync, install_silently, enable_on_install,
                           enable_incognito_on_install, install_source);
}

void ExtensionService::ReloadExtension(const std::string& extension_id) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  FilePath path;
  const Extension* current_extension = GetExtensionById(extension_id, false);

  // Disable the extension if it's loaded. It might not be loaded if it crashed.
  if (current_extension) {
    // If the extension has an inspector open for its background page, detach
    // the inspector and hang onto a cookie for it, so that we can reattach
    // later.
    ExtensionProcessManager* manager = profile_->GetExtensionProcessManager();
    ExtensionHost* host = manager->GetBackgroundHostForExtension(
        current_extension);
    if (host) {
      // Look for an open inspector for the background page.
      int devtools_cookie = DevToolsManager::GetInstance()->DetachClientHost(
          host->render_view_host());
      if (devtools_cookie >= 0)
        orphaned_dev_tools_[extension_id] = devtools_cookie;
    }

    path = current_extension->path();
    DisableExtension(extension_id);
    disabled_extension_paths_[extension_id] = path;
  } else {
    path = unloaded_extension_paths_[extension_id];
  }

  // Check the installed extensions to see if what we're reloading was already
  // installed.
  scoped_ptr<ExtensionInfo> installed_extension(
      extension_prefs_->GetInstalledExtensionInfo(extension_id));
  if (installed_extension.get() &&
      installed_extension->extension_manifest.get()) {
    LoadInstalledExtension(*installed_extension, false);
  } else {
    // We should always be able to remember the extension's path. If it's not in
    // the map, someone failed to update |unloaded_extension_paths_|.
    CHECK(!path.empty());
    LoadExtension(path);
  }
}

void ExtensionService::UninstallExtension(const std::string& extension_id,
                                           bool external_uninstall) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  const Extension* extension =
      GetExtensionByIdInternal(extension_id, true, true);
  if (!extension)
    extension = GetTerminatedExtension(extension_id);

  // Callers should not send us nonexistent extensions.
  CHECK(extension);

  // Get hold of information we need after unloading, since the extension
  // pointer will be invalid then.
  GURL extension_url(extension->url());
  Extension::Location location(extension->location());
  UninstalledExtensionInfo uninstalled_extension_info(*extension);

  UMA_HISTOGRAM_ENUMERATION("Extensions.UninstallType",
                            extension->GetType(), 100);

  // Also copy the extension identifier since the reference might have been
  // obtained via Extension::id().
  std::string extension_id_copy(extension_id);

  if (profile_->GetTemplateURLModel())
    profile_->GetTemplateURLModel()->UnregisterExtensionKeyword(extension);

  // Unload before doing more cleanup to ensure that nothing is hanging on to
  // any of these resources.
  UnloadExtension(extension_id, UnloadedExtensionInfo::UNINSTALL);

  extension_prefs_->OnExtensionUninstalled(extension_id_copy, location,
                                           external_uninstall);

  // Tell the backend to start deleting installed extensions on the file thread.
  if (Extension::LOAD != location) {
    BrowserThread::PostTask(
      BrowserThread::FILE, FROM_HERE,
      NewRunnableFunction(
          &extension_file_util::UninstallExtension,
          install_directory_,
          extension_id_copy));
  }

  ClearExtensionData(extension_url);
  UntrackTerminatedExtension(extension_id);

  // Notify interested parties that we've uninstalled this extension.
  NotificationService::current()->Notify(
      NotificationType::EXTENSION_UNINSTALLED,
      Source<Profile>(profile_),
      Details<UninstalledExtensionInfo>(&uninstalled_extension_info));
}

void ExtensionService::ClearExtensionData(const GURL& extension_url) {
  scoped_refptr<ExtensionDataDeleter> deleter(
      new ExtensionDataDeleter(profile_, extension_url));
  deleter->StartDeleting();
}

void ExtensionService::EnableExtension(const std::string& extension_id) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  const Extension* extension =
      GetExtensionByIdInternal(extension_id, false, true);
  if (!extension)
    return;

  extension_prefs_->SetExtensionState(extension, Extension::ENABLED);

  // Move it over to the enabled list.
  extensions_.push_back(make_scoped_refptr(extension));
  ExtensionList::iterator iter = std::find(disabled_extensions_.begin(),
                                           disabled_extensions_.end(),
                                           extension);
  disabled_extensions_.erase(iter);

  // Make sure any browser action contained within it is not hidden.
  extension_prefs_->SetBrowserActionVisibility(extension, true);

  ExtensionWebUI::RegisterChromeURLOverrides(profile_,
      extension->GetChromeURLOverrides());

  NotifyExtensionLoaded(extension);
  UpdateActiveExtensionsInCrashReporter();
}

void ExtensionService::DisableExtension(const std::string& extension_id) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  const Extension* extension =
      GetExtensionByIdInternal(extension_id, true, false);
  // The extension may have been disabled already.
  if (!extension)
    return;

  extension_prefs_->SetExtensionState(extension, Extension::DISABLED);

  // Move it over to the disabled list.
  disabled_extensions_.push_back(make_scoped_refptr(extension));
  ExtensionList::iterator iter = std::find(extensions_.begin(),
                                           extensions_.end(),
                                           extension);
  extensions_.erase(iter);

  ExtensionWebUI::UnregisterChromeURLOverrides(profile_,
      extension->GetChromeURLOverrides());

  NotifyExtensionUnloaded(extension, UnloadedExtensionInfo::DISABLE);
  UpdateActiveExtensionsInCrashReporter();
}

void ExtensionService::GrantPermissions(const Extension* extension) {
  CHECK(extension);

  // We only maintain the granted permissions prefs for INTERNAL extensions.
  CHECK(extension->location() == Extension::INTERNAL);

  ExtensionExtent effective_hosts = extension->GetEffectiveHostPermissions();
  extension_prefs_->AddGrantedPermissions(extension->id(),
                                          extension->HasFullPermissions(),
                                          extension->api_permissions(),
                                          effective_hosts);
}

void ExtensionService::GrantPermissionsAndEnableExtension(
    const Extension* extension) {
  CHECK(extension);
  GrantPermissions(extension);
  extension_prefs_->SetDidExtensionEscalatePermissions(extension, false);
  EnableExtension(extension->id());
}

void ExtensionService::LoadExtension(const FilePath& extension_path) {
  BrowserThread::PostTask(
      BrowserThread::FILE, FROM_HERE,
      NewRunnableMethod(
          backend_.get(),
          &ExtensionServiceBackend::LoadSingleExtension,
          extension_path, scoped_refptr<ExtensionService>(this)));
}

void ExtensionService::LoadComponentExtensions() {
  for (RegisteredComponentExtensions::iterator it =
           component_extension_manifests_.begin();
       it != component_extension_manifests_.end(); ++it) {
    JSONStringValueSerializer serializer(it->manifest);
    scoped_ptr<Value> manifest(serializer.Deserialize(NULL, NULL));
    if (!manifest.get()) {
      DLOG(ERROR) << "Failed to parse manifest for extension";
      continue;
    }

    std::string error;
    scoped_refptr<const Extension> extension(Extension::Create(
        it->root_directory,
        Extension::COMPONENT,
        *static_cast<DictionaryValue*>(manifest.get()),
        true,  // Require key
        Extension::ShouldDoStrictErrorChecking(Extension::COMPONENT),
        &error));
    if (!extension.get()) {
      NOTREACHED() << error;
      return;
    }
    AddExtension(extension);
  }
}

void ExtensionService::LoadAllExtensions() {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  base::TimeTicks start_time = base::TimeTicks::Now();

  // Load any component extensions.
  LoadComponentExtensions();

  // Load the previously installed extensions.
  scoped_ptr<ExtensionPrefs::ExtensionsInfo> extensions_info(
      extension_prefs_->GetInstalledExtensionsInfo());

  std::vector<int> reload_reason_counts(NUM_MANIFEST_RELOAD_REASONS, 0);
  bool should_write_prefs = false;

  for (size_t i = 0; i < extensions_info->size(); ++i) {
    ExtensionInfo* info = extensions_info->at(i).get();

    ManifestReloadReason reload_reason = ShouldReloadExtensionManifest(*info);
    ++reload_reason_counts[reload_reason];
    UMA_HISTOGRAM_ENUMERATION("Extensions.ManifestReloadEnumValue",
                              reload_reason, 100);

    if (reload_reason != NOT_NEEDED) {
      // Reloading and extension reads files from disk.  We do this on the
      // UI thread because reloads should be very rare, and the complexity
      // added by delaying the time when the extensions service knows about
      // all extensions is significant.  See crbug.com/37548 for details.
      // |allow_io| disables tests that file operations run on the file
      // thread.
      base::ThreadRestrictions::ScopedAllowIO allow_io;

      std::string error;
      scoped_refptr<const Extension> extension(
          extension_file_util::LoadExtension(
              info->extension_path,
              info->extension_location,
              false,  // Don't require key
              Extension::ShouldDoStrictErrorChecking(info->extension_location),
              &error));

      if (extension.get()) {
        extensions_info->at(i)->extension_manifest.reset(
            static_cast<DictionaryValue*>(
                extension->manifest_value()->DeepCopy()));
        should_write_prefs = true;
      }
    }
  }

  for (size_t i = 0; i < extensions_info->size(); ++i) {
    LoadInstalledExtension(*extensions_info->at(i), should_write_prefs);
  }

  OnLoadedInstalledExtensions();

  // The histograms Extensions.ManifestReload* allow us to validate
  // the assumption that reloading manifest is a rare event.
  UMA_HISTOGRAM_COUNTS_100("Extensions.ManifestReloadNotNeeded",
                           reload_reason_counts[NOT_NEEDED]);
  UMA_HISTOGRAM_COUNTS_100("Extensions.ManifestReloadUnpackedDir",
                           reload_reason_counts[UNPACKED_DIR]);
  UMA_HISTOGRAM_COUNTS_100("Extensions.ManifestReloadNeedsRelocalization",
                           reload_reason_counts[NEEDS_RELOCALIZATION]);

  UMA_HISTOGRAM_COUNTS_100("Extensions.LoadAll", extensions_.size());
  UMA_HISTOGRAM_COUNTS_100("Extensions.Disabled", disabled_extensions_.size());

  UMA_HISTOGRAM_TIMES("Extensions.LoadAllTime",
                      base::TimeTicks::Now() - start_time);

  int app_count = 0;
  int hosted_app_count = 0;
  int packaged_app_count = 0;
  int user_script_count = 0;
  int extension_count = 0;
  int theme_count = 0;
  int external_count = 0;
  int page_action_count = 0;
  int browser_action_count = 0;
  ExtensionList::iterator ex;
  for (ex = extensions_.begin(); ex != extensions_.end(); ++ex) {
    Extension::Location location = (*ex)->location();
    Extension::Type type = (*ex)->GetType();
    if ((*ex)->is_app()) {
      UMA_HISTOGRAM_ENUMERATION("Extensions.AppLocation",
                                location, 100);
    } else if (type == Extension::TYPE_EXTENSION) {
      UMA_HISTOGRAM_ENUMERATION("Extensions.ExtensionLocation",
                                location, 100);
    }

    // Don't count component extensions, since they are only extensions as an
    // implementation detail.
    if (location == Extension::COMPONENT)
      continue;

    // Don't count unpacked extensions, since they're a developer-specific
    // feature.
    if (location == Extension::LOAD)
      continue;

    // Using an enumeration shows us the total installed ratio across all users.
    // Using the totals per user at each startup tells us the distribution of
    // usage for each user (e.g. 40% of users have at least one app installed).
    UMA_HISTOGRAM_ENUMERATION("Extensions.LoadType", type, 100);
    switch (type) {
      case Extension::TYPE_THEME:
        ++theme_count;
        break;
      case Extension::TYPE_USER_SCRIPT:
        ++user_script_count;
        break;
      case Extension::TYPE_HOSTED_APP:
        ++app_count;
        ++hosted_app_count;
        break;
      case Extension::TYPE_PACKAGED_APP:
        ++app_count;
        ++packaged_app_count;
        break;
      case Extension::TYPE_EXTENSION:
      default:
        ++extension_count;
        break;
    }
    if (Extension::IsExternalLocation(location))
      ++external_count;
    if ((*ex)->page_action() != NULL)
      ++page_action_count;
    if ((*ex)->browser_action() != NULL)
      ++browser_action_count;
  }
  UMA_HISTOGRAM_COUNTS_100("Extensions.LoadApp", app_count);
  UMA_HISTOGRAM_COUNTS_100("Extensions.LoadHostedApp", hosted_app_count);
  UMA_HISTOGRAM_COUNTS_100("Extensions.LoadPackagedApp", packaged_app_count);
  UMA_HISTOGRAM_COUNTS_100("Extensions.LoadExtension", extension_count);
  UMA_HISTOGRAM_COUNTS_100("Extensions.LoadUserScript", user_script_count);
  UMA_HISTOGRAM_COUNTS_100("Extensions.LoadTheme", theme_count);
  UMA_HISTOGRAM_COUNTS_100("Extensions.LoadExternal", external_count);
  UMA_HISTOGRAM_COUNTS_100("Extensions.LoadPageAction", page_action_count);
  UMA_HISTOGRAM_COUNTS_100("Extensions.LoadBrowserAction",
                           browser_action_count);
}

void ExtensionService::LoadInstalledExtension(const ExtensionInfo& info,
                                              bool write_to_prefs) {
  std::string error;
  scoped_refptr<const Extension> extension(NULL);
  if (!extension_prefs_->IsExtensionAllowedByPolicy(info.extension_id)) {
    error = errors::kDisabledByPolicy;
  } else if (info.extension_manifest.get()) {
    bool require_key = info.extension_location != Extension::LOAD;
    extension = Extension::Create(
        info.extension_path,
        info.extension_location,
        *info.extension_manifest,
        require_key,
        Extension::ShouldDoStrictErrorChecking(info.extension_location),
        &error);
  } else {
    error = errors::kManifestUnreadable;
  }

  if (!extension) {
    ReportExtensionLoadError(info.extension_path,
                             error,
                             NotificationType::EXTENSION_INSTALL_ERROR,
                             false);
    return;
  }

  if (write_to_prefs)
    extension_prefs_->UpdateManifest(extension);

  AddExtension(extension);
}

void ExtensionService::NotifyExtensionLoaded(const Extension* extension) {
  // The ChromeURLRequestContexts need to be first to know that the extension
  // was loaded, otherwise a race can arise where a renderer that is created
  // for the extension may try to load an extension URL with an extension id
  // that the request context doesn't yet know about. The profile is responsible
  // for ensuring its URLRequestContexts appropriately discover the loaded
  // extension.
  if (profile_) {
    profile_->RegisterExtensionWithRequestContexts(extension);
    profile_->GetExtensionSpecialStoragePolicy()->
        GrantRightsForExtension(extension);
  }

  NotificationService::current()->Notify(
      NotificationType::EXTENSION_LOADED,
      Source<Profile>(profile_),
      Details<const Extension>(extension));
}

void ExtensionService::NotifyExtensionUnloaded(
    const Extension* extension, UnloadedExtensionInfo::Reason reason) {
  UnloadedExtensionInfo details(extension, reason);
  NotificationService::current()->Notify(
      NotificationType::EXTENSION_UNLOADED,
      Source<Profile>(profile_),
      Details<UnloadedExtensionInfo>(&details));

  if (profile_) {
    profile_->UnregisterExtensionWithRequestContexts(extension);
    profile_->GetExtensionSpecialStoragePolicy()->
        RevokeRightsForExtension(extension);
  }
}

void ExtensionService::UpdateExtensionBlacklist(
  const std::vector<std::string>& blacklist) {
  // Use this set to indicate if an extension in the blacklist has been used.
  std::set<std::string> blacklist_set;
  for (unsigned int i = 0; i < blacklist.size(); ++i) {
    if (Extension::IdIsValid(blacklist[i])) {
      blacklist_set.insert(blacklist[i]);
    }
  }
  extension_prefs_->UpdateBlacklist(blacklist_set);
  std::vector<std::string> to_be_removed;
  // Loop current extensions, unload installed extensions.
  for (ExtensionList::const_iterator iter = extensions_.begin();
       iter != extensions_.end(); ++iter) {
    const Extension* extension = (*iter);
    if (blacklist_set.find(extension->id()) != blacklist_set.end()) {
      to_be_removed.push_back(extension->id());
    }
  }

  // UnloadExtension will change the extensions_ list. So, we should
  // call it outside the iterator loop.
  for (unsigned int i = 0; i < to_be_removed.size(); ++i) {
    UnloadExtension(to_be_removed[i], UnloadedExtensionInfo::DISABLE);
  }
}

Profile* ExtensionService::profile() {
  return profile_;
}

void ExtensionService::DestroyingProfile() {
  if (updater_.get()) {
    updater_->Stop();
  }
  browser_event_router_.reset();
  pref_change_registrar_.RemoveAll();
  profile_ = NULL;
  toolbar_model_.DestroyingProfile();
}

ExtensionPrefs* ExtensionService::extension_prefs() {
  return extension_prefs_;
}

void ExtensionService::CheckAdminBlacklist() {
  std::vector<std::string> to_be_removed;
  // Loop through extensions list, unload installed extensions.
  for (ExtensionList::const_iterator iter = extensions_.begin();
       iter != extensions_.end(); ++iter) {
    const Extension* extension = (*iter);
    if (!extension_prefs_->IsExtensionAllowedByPolicy(extension->id()))
      to_be_removed.push_back(extension->id());
  }

  // UnloadExtension will change the extensions_ list. So, we should
  // call it outside the iterator loop.
  for (unsigned int i = 0; i < to_be_removed.size(); ++i)
    UnloadExtension(to_be_removed[i], UnloadedExtensionInfo::DISABLE);
}

bool ExtensionService::IsIncognitoEnabled(const Extension* extension) {
  // If this is a component extension we always allow it to work in incognito
  // mode.
  if (extension->location() == Extension::COMPONENT)
    return true;

  // Check the prefs.
  return extension_prefs_->IsIncognitoEnabled(extension->id());
}

void ExtensionService::SetIsIncognitoEnabled(const Extension* extension,
                                              bool enabled) {
  extension_prefs_->SetIsIncognitoEnabled(extension->id(), enabled);

  // Broadcast unloaded and loaded events to update browser state. Only bother
  // if the extension is actually enabled, since there is no UI otherwise.
  bool is_enabled = std::find(extensions_.begin(), extensions_.end(),
                              extension) != extensions_.end();
  if (is_enabled) {
    NotifyExtensionUnloaded(extension, UnloadedExtensionInfo::DISABLE);
    NotifyExtensionLoaded(extension);
  }
}

bool ExtensionService::CanCrossIncognito(const Extension* extension) {
  // We allow the extension to see events and data from another profile iff it
  // uses "spanning" behavior and it has incognito access. "split" mode
  // extensions only see events for a matching profile.
  return IsIncognitoEnabled(extension) && !extension->incognito_split_mode();
}

bool ExtensionService::AllowFileAccess(const Extension* extension) {
  return (CommandLine::ForCurrentProcess()->HasSwitch(
              switches::kDisableExtensionsFileAccessCheck) ||
          extension_prefs_->AllowFileAccess(extension->id()));
}

void ExtensionService::SetAllowFileAccess(const Extension* extension,
                                           bool allow) {
  extension_prefs_->SetAllowFileAccess(extension->id(), allow);
  NotificationService::current()->Notify(
      NotificationType::EXTENSION_USER_SCRIPTS_UPDATED,
      Source<Profile>(profile_),
      Details<const Extension>(extension));
}

bool ExtensionService::GetBrowserActionVisibility(const Extension* extension) {
  return extension_prefs_->GetBrowserActionVisibility(extension);
}

void ExtensionService::SetBrowserActionVisibility(const Extension* extension,
                                                  bool visible) {
  extension_prefs_->SetBrowserActionVisibility(extension, visible);
}

// Some extensions will autoupdate themselves externally from Chrome.  These
// are typically part of some larger client application package.  To support
// these, the extension will register its location in the the preferences file
// (and also, on Windows, in the registry) and this code will periodically
// check that location for a .crx file, which it will then install locally if
// a new version is available.
// Errors are reported through ExtensionErrorReporter. Succcess is not
// reported.
void ExtensionService::CheckForExternalUpdates() {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  // Note that this installation is intentionally silent (since it didn't
  // go through the front-end).  Extensions that are registered in this
  // way are effectively considered 'pre-bundled', and so implicitly
  // trusted.  In general, if something has HKLM or filesystem access,
  // they could install an extension manually themselves anyway.

  // If any external extension records give a URL, a provider will set
  // this to true.  Used by OnExternalProviderReady() to see if we need
  // to start an update check to fetch a new external extension.
  external_extension_url_added_ = false;

  // Ask each external extension provider to give us a call back for each
  // extension they know about. See OnExternalExtension(File|UpdateUrl)Found.
  ProviderCollection::const_iterator i;
  for (i = external_extension_providers_.begin();
       i != external_extension_providers_.end(); ++i) {
    ExternalExtensionProviderInterface* provider = i->get();
    provider->VisitRegisteredExtension();
  }

  // Uninstall of unclaimed extensions will happen after all the providers
  // had reported ready.  Every provider calls OnExternalProviderReady()
  // when it finishes, and OnExternalProviderReady() only acts when all
  // providers are ready.  In case there are no providers, we call it
  // to trigger removal of extensions that used to have an external source.
  if (external_extension_providers_.empty())
    OnExternalProviderReady();
}

void ExtensionService::OnExternalProviderReady() {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  // An external provider has finished loading.  We only take action
  // if all of them are finished. So we check them first.
  ProviderCollection::const_iterator i;
  for (i = external_extension_providers_.begin();
       i != external_extension_providers_.end(); ++i) {
    ExternalExtensionProviderInterface* provider = i->get();
    if (!provider->IsReady())
      return;
  }

  // All the providers are ready.  Install any pending extensions.
  if (external_extension_url_added_ && updater()) {
    external_extension_url_added_ = false;
    updater()->CheckNow();
  }

  // Uninstall all the unclaimed extensions.
  scoped_ptr<ExtensionPrefs::ExtensionsInfo> extensions_info(
      extension_prefs_->GetInstalledExtensionsInfo());
  for (size_t i = 0; i < extensions_info->size(); ++i) {
    ExtensionInfo* info = extensions_info->at(i).get();
    if (Extension::IsExternalLocation(info->extension_location))
      CheckExternalUninstall(info->extension_id);
  }
}

void ExtensionService::UnloadExtension(
    const std::string& extension_id,
    UnloadedExtensionInfo::Reason reason) {
  // Make sure the extension gets deleted after we return from this function.
  scoped_refptr<const Extension> extension(
      GetExtensionByIdInternal(extension_id, true, true));

  // This method can be called via PostTask, so the extension may have been
  // unloaded by the time this runs.
  if (!extension)
    return;

  // Keep information about the extension so that we can reload it later
  // even if it's not permanently installed.
  unloaded_extension_paths_[extension->id()] = extension->path();

  // Clean up if the extension is meant to be enabled after a reload.
  disabled_extension_paths_.erase(extension->id());

  // Clean up runtime data.
  extension_runtime_data_.erase(extension_id);

  ExtensionWebUI::UnregisterChromeURLOverrides(profile_,
      extension->GetChromeURLOverrides());

  ExtensionList::iterator iter = std::find(disabled_extensions_.begin(),
                                           disabled_extensions_.end(),
                                           extension.get());
  if (iter != disabled_extensions_.end()) {
    UnloadedExtensionInfo details(extension, reason);
    details.already_disabled = true;
    disabled_extensions_.erase(iter);
    NotificationService::current()->Notify(
        NotificationType::EXTENSION_UNLOADED,
        Source<Profile>(profile_),
        Details<UnloadedExtensionInfo>(&details));
    return;
  }

  iter = std::find(extensions_.begin(), extensions_.end(), extension.get());

  // Remove the extension from our list.
  extensions_.erase(iter);

  NotifyExtensionUnloaded(extension.get(), reason);
  UpdateActiveExtensionsInCrashReporter();
}

void ExtensionService::UnloadAllExtensions() {
  if (profile_) {
    profile_->GetExtensionSpecialStoragePolicy()->
        RevokeRightsForAllExtensions();
  }
  extensions_.clear();
  disabled_extensions_.clear();
  terminated_extension_ids_.clear();
  terminated_extensions_.clear();
  extension_runtime_data_.clear();

  // TODO(erikkay) should there be a notification for this?  We can't use
  // EXTENSION_UNLOADED since that implies that the extension has been disabled
  // or uninstalled, and UnloadAll is just part of shutdown.
}

void ExtensionService::ReloadExtensions() {
  UnloadAllExtensions();
  LoadAllExtensions();
}

void ExtensionService::GarbageCollectExtensions() {
  if (extension_prefs_->pref_service()->ReadOnly())
    return;

  scoped_ptr<ExtensionPrefs::ExtensionsInfo> info(
      extension_prefs_->GetInstalledExtensionsInfo());

  std::map<std::string, FilePath> extension_paths;
  for (size_t i = 0; i < info->size(); ++i)
    extension_paths[info->at(i)->extension_id] = info->at(i)->extension_path;

  BrowserThread::PostTask(
      BrowserThread::FILE, FROM_HERE,
      NewRunnableFunction(
          &extension_file_util::GarbageCollectExtensions, install_directory_,
          extension_paths));

  // Also garbage-collect themes.  We check |profile_| to be
  // defensive; in the future, we may call GarbageCollectExtensions()
  // from somewhere other than Init() (e.g., in a timer).
  if (profile_) {
    profile_->GetThemeProvider()->RemoveUnusedThemes();
  }
}

void ExtensionService::OnLoadedInstalledExtensions() {
  if (updater_.get()) {
    updater_->Start();
  }

  ready_ = true;
  NotificationService::current()->Notify(
      NotificationType::EXTENSIONS_READY,
      Source<Profile>(profile_),
      NotificationService::NoDetails());
}

void ExtensionService::AddExtension(const Extension* extension) {
  // Ensure extension is deleted unless we transfer ownership.
  scoped_refptr<const Extension> scoped_extension(extension);

  // The extension is now loaded, remove its data from unloaded extension map.
  unloaded_extension_paths_.erase(extension->id());

  // If a terminated extension is loaded, remove it from the terminated list.
  UntrackTerminatedExtension(extension->id());

  // If the extension was disabled for a reload, then enable it.
  if (disabled_extension_paths_.erase(extension->id()) > 0)
    EnableExtension(extension->id());

  // TODO(jstritar): We may be able to get rid of this branch by overriding the
  // default extension state to DISABLED when the --disable-extensions flag
  // is set (http://crbug.com/29067).
  if (!extensions_enabled() &&
      !extension->is_theme() &&
      extension->location() != Extension::COMPONENT &&
      !Extension::IsExternalLocation(extension->location()))
    return;

  // Check if the extension's privileges have changed and disable the
  // extension if necessary.
  DisableIfPrivilegeIncrease(extension);

  switch (extension_prefs_->GetExtensionState(extension->id())) {
    case Extension::ENABLED:
      extensions_.push_back(scoped_extension);

      NotifyExtensionLoaded(extension);

      ExtensionWebUI::RegisterChromeURLOverrides(
          profile_, extension->GetChromeURLOverrides());
      break;
    case Extension::DISABLED:
      disabled_extensions_.push_back(scoped_extension);
      NotificationService::current()->Notify(
          NotificationType::EXTENSION_UPDATE_DISABLED,
          Source<Profile>(profile_),
          Details<const Extension>(extension));
      break;
    default:
      NOTREACHED();
      break;
  }

  SetBeingUpgraded(extension, false);

  UpdateActiveExtensionsInCrashReporter();

  if (profile_->GetTemplateURLModel())
    profile_->GetTemplateURLModel()->RegisterExtensionKeyword(extension);

  // Load the icon for omnibox-enabled extensions so it will be ready to display
  // in the URL bar.
  if (!extension->omnibox_keyword().empty()) {
    omnibox_popup_icon_manager_.LoadIcon(extension);
    omnibox_icon_manager_.LoadIcon(extension);
  }
}

void ExtensionService::DisableIfPrivilegeIncrease(const Extension* extension) {
  // We keep track of all permissions the user has granted each extension.
  // This allows extensions to gracefully support backwards compatibility
  // by including unknown permissions in their manifests. When the user
  // installs the extension, only the recognized permissions are recorded.
  // When the unknown permissions become recognized (e.g., through browser
  // upgrade), we can prompt the user to accept these new permissions.
  // Extensions can also silently upgrade to less permissions, and then
  // silently upgrade to a version that adds these permissions back.
  //
  // For example, pretend that Chrome 10 includes a permission "omnibox"
  // for an API that adds suggestions to the omnibox. An extension can
  // maintain backwards compatibility while still having "omnibox" in the
  // manifest. If a user installs the extension on Chrome 9, the browser
  // will record the permissions it recognized, not including "omnibox."
  // When upgrading to Chrome 10, "omnibox" will be recognized and Chrome
  // will disable the extension and prompt the user to approve the increase
  // in privileges. The extension could then release a new version that
  // removes the "omnibox" permission. When the user upgrades, Chrome will
  // still remember that "omnibox" had been granted, so that if the
  // extension once again includes "omnibox" in an upgrade, the extension
  // can upgrade without requiring this user's approval.
  const Extension* old = GetExtensionByIdInternal(extension->id(),
                                                  true, true);
  bool granted_full_access;
  std::set<std::string> granted_apis;
  ExtensionExtent granted_extent;

  bool is_extension_upgrade = old != NULL;
  bool is_privilege_increase = false;

  // We only record the granted permissions for INTERNAL extensions, since
  // they can't silently increase privileges.
  if (extension->location() == Extension::INTERNAL) {
    // Add all the recognized permissions if the granted permissions list
    // hasn't been initialized yet.
    if (!extension_prefs_->GetGrantedPermissions(extension->id(),
                                                 &granted_full_access,
                                                 &granted_apis,
                                                 &granted_extent)) {
      GrantPermissions(extension);
      CHECK(extension_prefs_->GetGrantedPermissions(extension->id(),
                                                    &granted_full_access,
                                                    &granted_apis,
                                                    &granted_extent));
    }

    // Here, we check if an extension's privileges have increased in a manner
    // that requires the user's approval. This could occur because the browser
    // upgraded and recognized additional privileges, or an extension upgrades
    // to a version that requires additional privileges.
    is_privilege_increase = Extension::IsPrivilegeIncrease(
        granted_full_access, granted_apis, granted_extent, extension);
  }

  if (is_extension_upgrade) {
    // Other than for unpacked extensions, CrxInstaller should have guaranteed
    // that we aren't downgrading.
    if (extension->location() != Extension::LOAD)
      CHECK(extension->version()->CompareTo(*(old->version())) >= 0);

    // Extensions get upgraded if the privileges are allowed to increase or
    // the privileges haven't increased.
    if (!is_privilege_increase) {
      SetBeingUpgraded(old, true);
      SetBeingUpgraded(extension, true);
    }

    // To upgrade an extension in place, unload the old one and
    // then load the new one.
    UnloadExtension(old->id(), UnloadedExtensionInfo::UPDATE);
    old = NULL;
  }

  // Extension has changed permissions significantly. Disable it. A
  // notification should be sent by the caller.
  if (is_privilege_increase) {
    extension_prefs_->SetExtensionState(extension, Extension::DISABLED);
    extension_prefs_->SetDidExtensionEscalatePermissions(extension, true);
  }
}

void ExtensionService::UpdateActiveExtensionsInCrashReporter() {
  std::set<std::string> extension_ids;
  for (size_t i = 0; i < extensions_.size(); ++i) {
    if (!extensions_[i]->is_theme() &&
        extensions_[i]->location() != Extension::COMPONENT)
      extension_ids.insert(extensions_[i]->id());
  }

  child_process_logging::SetActiveExtensions(extension_ids);
}

void ExtensionService::OnExtensionInstalled(const Extension* extension) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  // Ensure extension is deleted unless we transfer ownership.
  scoped_refptr<const Extension> scoped_extension(extension);
  Extension::State initial_state = Extension::DISABLED;
  bool initial_enable_incognito = false;
  PendingExtensionMap::iterator it =
      pending_extensions_.find(extension->id());
  if (it != pending_extensions_.end()) {
    PendingExtensionInfo pending_extension_info = it->second;
    pending_extensions_.erase(it);
    it = pending_extensions_.end();

    if (!pending_extension_info.ShouldAllowInstall(*extension)) {
      LOG(WARNING)
          << "should_install_extension() returned false for "
          << extension->id() << " of type " << extension->GetType()
          << " and update URL " << extension->update_url().spec()
          << "; not installing";
      // Delete the extension directory since we're not going to
      // load it.
      BrowserThread::PostTask(
          BrowserThread::FILE, FROM_HERE,
          NewRunnableFunction(&extension_file_util::DeleteFile, extension->path(), true));
      return;
    }

    if (extension->is_theme()) {
      DCHECK(pending_extension_info.enable_on_install());
      initial_state = Extension::ENABLED;
      DCHECK(!pending_extension_info.enable_incognito_on_install());
      initial_enable_incognito = false;
    } else {
      initial_state =
          pending_extension_info.enable_on_install() ?
          Extension::ENABLED : Extension::DISABLED;
      initial_enable_incognito =
          pending_extension_info.enable_incognito_on_install();
    }
  } else {
    // Make sure we preserve enabled/disabled states.
    Extension::State existing_state =
        extension_prefs_->GetExtensionState(extension->id());
    initial_state =
        (existing_state == Extension::DISABLED) ?
        Extension::DISABLED : Extension::ENABLED;
    initial_enable_incognito =
        extension_prefs_->IsIncognitoEnabled(extension->id());
  }

  UMA_HISTOGRAM_ENUMERATION("Extensions.InstallType",
                            extension->GetType(), 100);
  ShownSectionsHandler::OnExtensionInstalled(profile_->GetPrefs(), extension);
  extension_prefs_->OnExtensionInstalled(
      extension, initial_state, initial_enable_incognito);

  // Unpacked extensions start off with file access since they are a developer
  // feature.
  if (extension->location() == Extension::LOAD)
    extension_prefs_->SetAllowFileAccess(extension->id(), true);

  // If the extension is a theme, tell the profile (and therefore ThemeProvider)
  // to apply it.
  if (extension->is_theme()) {
    NotificationService::current()->Notify(
        NotificationType::THEME_INSTALLED,
        Source<Profile>(profile_),
        Details<const Extension>(extension));
  } else {
    NotificationService::current()->Notify(
        NotificationType::EXTENSION_INSTALLED,
        Source<Profile>(profile_),
        Details<const Extension>(extension));
  }

  if (extension->is_app()) {
    ExtensionIdSet installed_ids = GetAppIds();
    installed_ids.insert(extension->id());
    default_apps_.DidInstallApp(installed_ids);
  }

  // Transfer ownership of |extension| to AddExtension.
  AddExtension(scoped_extension);
}

const Extension* ExtensionService::GetExtensionByIdInternal(
    const std::string& id, bool include_enabled, bool include_disabled) {
  std::string lowercase_id = StringToLowerASCII(id);
  if (include_enabled) {
    for (ExtensionList::const_iterator iter = extensions_.begin();
        iter != extensions_.end(); ++iter) {
      if ((*iter)->id() == lowercase_id)
        return *iter;
    }
  }
  if (include_disabled) {
    for (ExtensionList::const_iterator iter = disabled_extensions_.begin();
        iter != disabled_extensions_.end(); ++iter) {
      if ((*iter)->id() == lowercase_id)
        return *iter;
    }
  }
  return NULL;
}

void ExtensionService::TrackTerminatedExtension(const Extension* extension) {
  if (terminated_extension_ids_.insert(extension->id()).second)
    terminated_extensions_.push_back(make_scoped_refptr(extension));
}

void ExtensionService::UntrackTerminatedExtension(const std::string& id) {
  if (terminated_extension_ids_.erase(id) <= 0)
    return;

  std::string lowercase_id = StringToLowerASCII(id);
  for (ExtensionList::iterator iter = terminated_extensions_.begin();
       iter != terminated_extensions_.end(); ++iter) {
    if ((*iter)->id() == lowercase_id) {
      terminated_extensions_.erase(iter);
      return;
    }
  }
}

const Extension* ExtensionService::GetTerminatedExtension(
    const std::string& id) {
  std::string lowercase_id = StringToLowerASCII(id);
  for (ExtensionList::const_iterator iter = terminated_extensions_.begin();
       iter != terminated_extensions_.end(); ++iter) {
    if ((*iter)->id() == lowercase_id)
      return *iter;
  }
  return NULL;
}

const Extension* ExtensionService::GetWebStoreApp() {
  return GetExtensionById(extension_misc::kWebStoreAppId, false);
}

const Extension* ExtensionService::GetExtensionByURL(const GURL& url) {
  return url.scheme() != chrome::kExtensionScheme ? NULL :
      GetExtensionById(url.host(), false);
}

const Extension* ExtensionService::GetExtensionByWebExtent(const GURL& url) {
  for (size_t i = 0; i < extensions_.size(); ++i) {
    if (extensions_[i]->web_extent().ContainsURL(url))
      return extensions_[i];
  }
  return NULL;
}

bool ExtensionService::ExtensionBindingsAllowed(const GURL& url) {
  // Allow bindings for all packaged extension.
  if (GetExtensionByURL(url))
    return true;

  // Allow bindings for all component, hosted apps.
  const Extension* extension = GetExtensionByWebExtent(url);
  return (extension && extension->location() == Extension::COMPONENT);
}

const Extension* ExtensionService::GetExtensionByOverlappingWebExtent(
    const ExtensionExtent& extent) {
  for (size_t i = 0; i < extensions_.size(); ++i) {
    if (extensions_[i]->web_extent().OverlapsWith(extent))
      return extensions_[i];
  }

  return NULL;
}

const SkBitmap& ExtensionService::GetOmniboxIcon(
    const std::string& extension_id) {
  return omnibox_icon_manager_.GetIcon(extension_id);
}

const SkBitmap& ExtensionService::GetOmniboxPopupIcon(
    const std::string& extension_id) {
  return omnibox_popup_icon_manager_.GetIcon(extension_id);
}

void ExtensionService::OnExternalExtensionFileFound(
         const std::string& id,
         const Version* version,
         const FilePath& path,
         Extension::Location location) {
  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  CHECK(Extension::IdIsValid(id));
  if (extension_prefs_->IsExtensionKilled(id))
    return;

  DCHECK(version);

  // Before even bothering to unpack, check and see if we already have this
  // version. This is important because these extensions are going to get
  // installed on every startup.
  const Extension* existing = GetExtensionById(id, true);
  if (existing) {
    switch (existing->version()->CompareTo(*version)) {
      case -1:  // existing version is older, we should upgrade
        break;
      case 0:  // existing version is same, do nothing
        return;
      case 1:  // existing version is newer, uh-oh
        LOG(WARNING) << "Found external version of extension " << id
                     << "that is older than current version. Current version "
                     << "is: " << existing->VersionString() << ". New version "
                     << "is: " << version << ". Keeping current version.";
        return;
    }
  }

  GURL update_url = GURL();
  bool is_from_sync = false;
  bool install_silently = true;
  bool enable_on_install = true;
  bool enable_incognito_on_install = false;
  pending_extensions_[id] = PendingExtensionInfo(
      update_url,
      &AlwaysInstall,
      is_from_sync,
      install_silently,
      enable_on_install,
      enable_incognito_on_install,
      location);

  scoped_refptr<CrxInstaller> installer(
      new CrxInstaller(this,  // frontend
                       NULL));  // no client (silent install)
  installer->set_install_source(location);
  installer->set_expected_id(id);
  installer->InstallCrx(path);
}

void ExtensionService::ReportExtensionLoadError(
    const FilePath& extension_path,
    const std::string &error,
    NotificationType type,
    bool be_noisy) {
  NotificationService* service = NotificationService::current();
  service->Notify(type,
                  Source<Profile>(profile_),
                  Details<const std::string>(&error));

  std::string path_str = UTF16ToUTF8(extension_path.LossyDisplayName());
  std::string message = base::StringPrintf(
      "Could not load extension from '%s'. %s",
      path_str.c_str(), error.c_str());
  ExtensionErrorReporter::GetInstance()->ReportError(message, be_noisy);
}

void ExtensionService::DidCreateRenderViewForBackgroundPage(
    ExtensionHost* host) {
  OrphanedDevTools::iterator iter =
      orphaned_dev_tools_.find(host->extension()->id());
  if (iter == orphaned_dev_tools_.end())
    return;

  DevToolsManager::GetInstance()->AttachClientHost(
      iter->second, host->render_view_host());
  orphaned_dev_tools_.erase(iter);
}

void ExtensionService::Observe(NotificationType type,
                                const NotificationSource& source,
                                const NotificationDetails& details) {
  switch (type.value) {
    case NotificationType::EXTENSION_PROCESS_TERMINATED: {
      if (profile_ != Source<Profile>(source).ptr()->GetOriginalProfile())
        break;

      ExtensionHost* host = Details<ExtensionHost>(details).ptr();
      TrackTerminatedExtension(host->extension());

      // Unload the entire extension. We want it to be in a consistent state:
      // either fully working or not loaded at all, but never half-crashed.
      // We do it in a PostTask so that other handlers of this notification will
      // still have access to the Extension and ExtensionHost.
      MessageLoop::current()->PostTask(FROM_HERE,
          NewRunnableMethod(this,
                            &ExtensionService::UnloadExtension,
                            host->extension()->id(),
                            UnloadedExtensionInfo::DISABLE));
      break;
    }

    case NotificationType::PREF_CHANGED: {
      std::string* pref_name = Details<std::string>(details).ptr();
      if (*pref_name == prefs::kExtensionInstallAllowList ||
          *pref_name == prefs::kExtensionInstallDenyList) {
        CheckAdminBlacklist();
      } else {
        NOTREACHED() << "Unexpected preference name.";
      }
      break;
    }

    default:
      NOTREACHED() << "Unexpected notification type.";
  }
}

bool ExtensionService::HasApps() const {
  return !GetAppIds().empty();
}

ExtensionIdSet ExtensionService::GetAppIds() const {
  ExtensionIdSet result;
  for (ExtensionList::const_iterator it = extensions_.begin();
       it != extensions_.end(); ++it) {
    if ((*it)->is_app() && (*it)->location() != Extension::COMPONENT)
      result.insert((*it)->id());
  }

  return result;
}

bool ExtensionService::IsBackgroundPageReady(const Extension* extension) {
  return (extension->background_url().is_empty() ||
          extension_runtime_data_[extension->id()].background_page_ready);
}

void ExtensionService::SetBackgroundPageReady(const Extension* extension) {
  DCHECK(!extension->background_url().is_empty());
  extension_runtime_data_[extension->id()].background_page_ready = true;
  NotificationService::current()->Notify(
      NotificationType::EXTENSION_BACKGROUND_PAGE_READY,
      Source<const Extension>(extension),
      NotificationService::NoDetails());
}

bool ExtensionService::IsBeingUpgraded(const Extension* extension) {
  return extension_runtime_data_[extension->id()].being_upgraded;
}

void ExtensionService::SetBeingUpgraded(const Extension* extension,
                                         bool value) {
  extension_runtime_data_[extension->id()].being_upgraded = value;
}

PropertyBag* ExtensionService::GetPropertyBag(const Extension* extension) {
  return &extension_runtime_data_[extension->id()].property_bag;
}