Revert "Automatically trigger installation of high-quality speech synthesis extension."

This reverts commit r241081.

Reason: changing the builtin tts engine to use an event page instead of a persistent background page can cause tts to stop working for some users.

BUG=339322
TBR=dpolukhin@chromium.org, thakis@chromium.org, dtseng@chromium.org, kalman@chromium.org, dmazzoni@chromium.org

Review URL: https://codereview.chromium.org/149233004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249559 0039d316-1c4b-4281-b951-d872f2087c98

21 files changed, 247 insertions, 363 deletions

diff --git a/chrome/browser/chromeos/login/user_manager_impl.h b/chrome/browser/chromeos/login/user_manager_impl.h
index 0e27d08..5c80cc6 100644
--- a/chrome/browser/chromeos/login/user_manager_impl.h
+++ b/chrome/browser/chromeos/login/user_manager_impl.h
@@ -33,10 +33,6 @@
 class PrefService;
 class ProfileSyncService;
 
-namespace extensions {
-class ExternalComponentLoaderTest;
-}
-
 namespace policy {
 struct DeviceLocalAccount;
 }
@@ -172,7 +168,6 @@ class UserManagerImpl
   void StopPolicyObserverForTesting();
 
  private:
-  friend class extensions::ExternalComponentLoaderTest;
   friend class SupervisedUserManagerImpl;
   friend class UserManager;
   friend class WallpaperManager;
diff --git a/chrome/browser/extensions/component_loader.cc b/chrome/browser/extensions/component_loader.cc
index 0ef7a9f..e31c954 100644
--- a/chrome/browser/extensions/component_loader.cc
+++ b/chrome/browser/extensions/component_loader.cc
@@ -333,13 +333,6 @@ void ComponentLoader::AddNetworkSpeechSynthesisExtension() {
       base::FilePath(FILE_PATH_LITERAL("network_speech_synthesis")));
 }
 
-#if defined(OS_CHROMEOS)
-void ComponentLoader::AddChromeOsSpeechSynthesisExtension() {
-  Add(IDR_SPEECH_SYNTHESIS_MANIFEST,
-      base::FilePath(extension_misc::kSpeechSynthesisExtensionPath));
-}
-#endif
-
 void ComponentLoader::AddWithName(int manifest_resource_id,
                                   const base::FilePath& root_directory,
                                   const std::string& name) {
@@ -433,10 +426,6 @@ void ComponentLoader::AddDefaultComponentExtensionsForKioskMode(
 
   // Component extensions needed for kiosk apps.
   AddFileManagerExtension();
-
-#if defined(OS_CHROMEOS)
-  ComponentLoader::AddChromeOsSpeechSynthesisExtension();
-#endif
 }
 
 void ComponentLoader::AddDefaultComponentExtensionsWithBackgroundPages(
@@ -585,10 +574,6 @@ void ComponentLoader::AddDefaultComponentExtensionsWithBackgroundPages(
 #endif
 #endif  // defined(GOOGLE_CHROME_BUILD)
 
-#if defined(OS_CHROMEOS)
-  AddChromeOsSpeechSynthesisExtension();
-#endif  // defined(OS_CHROMEOS)
-
 #if defined(ENABLE_PLUGINS)
   base::FilePath pdf_path;
   content::PluginService* plugin_service =
diff --git a/chrome/browser/extensions/component_loader.h b/chrome/browser/extensions/component_loader.h
index bef24f9..816d1ea 100644
--- a/chrome/browser/extensions/component_loader.h
+++ b/chrome/browser/extensions/component_loader.h
@@ -126,9 +126,6 @@ class ComponentLoader {
   void AddImageLoaderExtension();
   void AddBookmarksExtensions();
   void AddNetworkSpeechSynthesisExtension();
-#if defined(OS_CHROMEOS)
-  void AddChromeOsSpeechSynthesisExtension();
-#endif
 
   void AddWithName(int manifest_resource_id,
                    const base::FilePath& root_directory,
diff --git a/chrome/browser/extensions/external_component_loader.cc b/chrome/browser/extensions/external_component_loader.cc
index 1b6e2b9..579a38b 100644
--- a/chrome/browser/extensions/external_component_loader.cc
+++ b/chrome/browser/extensions/external_component_loader.cc
@@ -20,40 +20,13 @@
 
 namespace extensions {
 
-#if defined(OS_CHROMEOS)
-namespace {
-// Table mapping language codes to the extension ids of high-quality
-// speech synthesis extensions. See the comment in StartLoading() for more.
-struct LangToExtensionId {
-  const char* lang;
-  const char* extension_id;
-};
-LangToExtensionId kLangToExtensionIdTable[] = {
-  { "en-US", extension_misc::kHighQuality_en_US_ExtensionId }
-};
-}  // anonymous namespace
-#endif  // defined(OS_CHROMEOS)
-
 ExternalComponentLoader::ExternalComponentLoader(Profile* profile)
     : profile_(profile) {
-#if defined(OS_CHROMEOS)
-  pref_change_registrar_.reset(new PrefChangeRegistrar());
-  pref_change_registrar_->Init(profile->GetPrefs());
-  pref_change_registrar_->Add(
-      prefs::kHighQualitySpeechSynthesisLanguages,
-      base::Bind(&ExternalComponentLoader::StartLoading, AsWeakPtr()));
-
-  for (size_t i = 0; i < arraysize(kLangToExtensionIdTable); ++i) {
-    lang_to_extension_id_map_[kLangToExtensionIdTable[i].lang] =
-        kLangToExtensionIdTable[i].extension_id;
-  }
-#endif
 }
 
 ExternalComponentLoader::~ExternalComponentLoader() {}
 
 void ExternalComponentLoader::StartLoading() {
-  CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   prefs_.reset(new base::DictionaryValue());
   std::string appId = extension_misc::kInAppPaymentsSupportAppId;
   prefs_->SetString(appId + ".external_update_url",
@@ -73,48 +46,7 @@ void ExternalComponentLoader::StartLoading() {
                         extension_urls::GetWebstoreUpdateUrl().spec());
     }
   }
-
-#if defined(OS_CHROMEOS)
-  // Chrome OS comes with medium-quality speech synthesis extensions built-in.
-  // When the user speaks a certain threshold of utterances in the same
-  // session, we set a preference indicating that high quality speech is
-  // enabled for that language. Here, we check the preference and prepare
-  // the list of external extensions to be installed based on that.
-  PrefService* pref_service = profile_->GetPrefs();
-  const base::ListValue* languages =
-      pref_service->GetList(prefs::kHighQualitySpeechSynthesisLanguages);
-  for (size_t i = 0; i < languages->GetSize(); ++i) {
-    std::string lang;
-    if (!languages->GetString(i, &lang))
-      continue;
-
-    base::hash_map<std::string, std::string>::iterator iter =
-        lang_to_extension_id_map_.find(lang);
-    if (iter == lang_to_extension_id_map_.end())
-      continue;
-
-    std::string extension_id = iter->second;
-    base::DictionaryValue* extension = new base::DictionaryValue();
-    prefs_->Set(extension_id, extension);
-    extension->SetString(ExternalProviderImpl::kExternalUpdateUrl,
-                         extension_urls::GetWebstoreUpdateUrl().spec());
-    base::ListValue* supported_locales = new base::ListValue();
-    supported_locales->AppendString(g_browser_process->GetApplicationLocale());
-    extension->Set(ExternalProviderImpl::kSupportedLocales, supported_locales);
-    extension->SetBoolean(ExternalProviderImpl::kIsFromWebstore, true);
-  }
-#endif  // defined(OS_CHROMEOS)
-
   LoadFinished();
 }
 
-// static
-void ExternalComponentLoader::RegisterProfilePrefs(
-    user_prefs::PrefRegistrySyncable* registry) {
-#if defined(OS_CHROMEOS)
-  registry->RegisterListPref(prefs::kHighQualitySpeechSynthesisLanguages,
-                             user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
-#endif
-}
-
 }  // namespace extensions
diff --git a/chrome/browser/extensions/external_component_loader.h b/chrome/browser/extensions/external_component_loader.h
index b27d504..02bb459 100644
--- a/chrome/browser/extensions/external_component_loader.h
+++ b/chrome/browser/extensions/external_component_loader.h
@@ -8,13 +8,9 @@
 #include <string>
 
 #include "base/compiler_specific.h"
-#include "base/containers/hash_tables.h"
-#include "base/memory/weak_ptr.h"
 #include "chrome/browser/extensions/external_loader.h"
 #include "chrome/browser/profiles/profile.h"
 
-class PrefChangeRegistrar;
-
 namespace extensions {
 
 // A specialization of the ExternalLoader that loads a hard-coded list of
@@ -23,17 +19,12 @@ namespace extensions {
 // and don't get access to component only APIs.
 // Instances of this class are expected to be created and destroyed on the UI
 // thread and they are expecting public method calls from the UI thread.
-class ExternalComponentLoader
-    : public ExternalLoader,
-      public base::SupportsWeakPtr<ExternalComponentLoader> {
+class ExternalComponentLoader : public ExternalLoader {
  public:
   explicit ExternalComponentLoader(Profile* profile);
 
   static bool IsEnhancedBookmarksExperimentEnabled();
 
-  // Register speech synthesis prefs for a profile.
-  static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
-
  protected:
   virtual void StartLoading() OVERRIDE;
 
@@ -44,17 +35,6 @@ class ExternalComponentLoader
   // The profile that this loader is associated with. It listens for
   // preference changes for that profile.
   Profile* profile_;
-
-#if defined(OS_CHROMEOS)
-  // The pref change registrar, so we can watch for pref changes.
-  scoped_ptr<PrefChangeRegistrar> pref_change_registrar_;
-
-  // A map from language code to the extension id of the high-quality
-  // extension for that language in the web store, if any - for loading
-  // speech synthesis component extensions.
-  base::hash_map<std::string, std::string> lang_to_extension_id_map_;
-#endif
-
   DISALLOW_COPY_AND_ASSIGN(ExternalComponentLoader);
 };
 
diff --git a/chrome/browser/extensions/external_component_loader_unittest.cc b/chrome/browser/extensions/external_component_loader_unittest.cc
deleted file mode 100644
index 6fb03ee..0000000
--- a/chrome/browser/extensions/external_component_loader_unittest.cc
+++ /dev/null
@@ -1,166 +0,0 @@
-// Copyright 2013 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/external_component_loader.h"
-
-#include "base/values.h"
-#include "chrome/browser/extensions/external_provider_impl.h"
-#include "chrome/browser/profiles/profile.h"
-#include "chrome/browser/speech/tts_platform.h"
-#include "chrome/common/extensions/extension_constants.h"
-#include "chrome/test/base/testing_profile.h"
-#include "content/public/test/test_browser_thread.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-#if defined(OS_CHROMEOS)
-#include "chrome/browser/chromeos/login/user_manager_impl.h"
-#include "chrome/browser/chromeos/settings/cros_settings.h"
-#include "chrome/browser/chromeos/settings/device_settings_service.h"
-#endif  // defined(OS_CHROMEOS)
-
-using content::BrowserThread;
-using extensions::ExternalProviderImpl;
-using extensions::ExternalProviderInterface;
-using extensions::Manifest;
-using extensions::ProviderCollection;
-
-namespace extensions {
-
-namespace {
-class TestUtterance : public Utterance {
- public:
-  explicit TestUtterance(Profile* profile) : Utterance(profile) {
-  }
-
-  virtual ~TestUtterance() {
-    set_finished_for_testing(true);
-  }
-};
-
-class FakeVisitorInterface
-    : public ExternalProviderInterface::VisitorInterface {
- public:
-  FakeVisitorInterface() {}
-  virtual ~FakeVisitorInterface() {}
-
-  virtual bool OnExternalExtensionFileFound(
-      const std::string& id,
-      const base::Version* version,
-      const base::FilePath& path,
-      Manifest::Location location,
-      int creation_flags,
-      bool mark_acknowledged) OVERRIDE {
-    return true;
-  }
-
-  virtual bool OnExternalExtensionUpdateUrlFound(
-      const std::string& id,
-      const GURL& update_url,
-      Manifest::Location location,
-      int creation_flags,
-      bool mark_acknowledged) OVERRIDE {
-    return true;
-  }
-
-  virtual void OnExternalProviderReady(
-      const ExternalProviderInterface* provider) OVERRIDE {}
-};
-}  // anonymous namespace
-
-#if defined(OS_CHROMEOS)
-class ExternalComponentLoaderTest : public testing::Test {
- public:
-  ExternalComponentLoaderTest()
-      : ui_thread_(BrowserThread::UI, &message_loop_),
-        user_manager_enabler_(new chromeos::UserManagerImpl()) {
-  }
-
-  virtual ~ExternalComponentLoaderTest() {}
-
-  // testing::Test overrides:
-  virtual void SetUp() OVERRIDE {
-    testing_profile_.reset(new TestingProfile());
-    ExternalProviderImpl::CreateExternalProviders(
-        &service_, testing_profile_.get(), &providers_);
-  }
-
-  virtual void TearDown() OVERRIDE {
-  }
-
-  bool IsHighQualityEnglishSpeechExtensionInstalled() {
-    const std::string& id = extension_misc::kHighQuality_en_US_ExtensionId;
-    for (size_t i = 0; i < providers_.size(); ++i) {
-      if (!providers_[i]->IsReady())
-        continue;
-      if (providers_[i]->HasExtension(id))
-        return true;
-    }
-    return false;
-  }
-
- protected:
-  base::MessageLoop message_loop_;
-  content::TestBrowserThread ui_thread_;
-  chromeos::ScopedTestDeviceSettingsService test_device_settings_service_;
-  chromeos::ScopedTestCrosSettings test_cros_settings_;
-  chromeos::ScopedUserManagerEnabler user_manager_enabler_;
-  scoped_ptr<Profile> testing_profile_;
-  FakeVisitorInterface service_;
-  ProviderCollection providers_;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(ExternalComponentLoaderTest);
-};
-
-TEST_F(ExternalComponentLoaderTest, Speaking100TimesInstallsSpeechExtension) {
-  ASSERT_FALSE(IsHighQualityEnglishSpeechExtensionInstalled());
-
-  TtsPlatformImpl* tts_platform = TtsPlatformImpl::GetInstance();
-  TestUtterance utterance(testing_profile_.get());
-  VoiceData voice_data;
-  voice_data.lang = "en-US";
-  voice_data.extension_id = extension_misc::kSpeechSynthesisExtensionId;
-
-  // 99 times should not be sufficient.
-  for (int i = 0; i < 99; i++)
-    tts_platform->WillSpeakUtteranceWithVoice(&utterance, voice_data);
-  ASSERT_FALSE(IsHighQualityEnglishSpeechExtensionInstalled());
-
-  // The 100th time should install it.
-  tts_platform->WillSpeakUtteranceWithVoice(&utterance, voice_data);
-  ASSERT_TRUE(IsHighQualityEnglishSpeechExtensionInstalled());
-}
-
-TEST_F(ExternalComponentLoaderTest,
-       UsingOtherVoiceDoesNotTriggerInstallingSpeechExtension) {
-  ASSERT_FALSE(IsHighQualityEnglishSpeechExtensionInstalled());
-
-  TtsPlatformImpl* tts_platform = TtsPlatformImpl::GetInstance();
-  TestUtterance utterance(testing_profile_.get());
-  VoiceData voice_data;
-  voice_data.lang = "en-US";
-  voice_data.extension_id = "dummy";  // Some other extension id.
-
-  for (int i = 0; i < 100; i++)
-    tts_platform->WillSpeakUtteranceWithVoice(&utterance, voice_data);
-  ASSERT_FALSE(IsHighQualityEnglishSpeechExtensionInstalled());
-}
-
-TEST_F(ExternalComponentLoaderTest,
-       UnsupportedLangDoesNotTriggerInstallingSpeechExtension) {
-  ASSERT_FALSE(IsHighQualityEnglishSpeechExtensionInstalled());
-
-  TtsPlatformImpl* tts_platform = TtsPlatformImpl::GetInstance();
-  TestUtterance utterance(testing_profile_.get());
-  VoiceData voice_data;
-  voice_data.lang = "tlh";  // Klingon
-  voice_data.extension_id = extension_misc::kSpeechSynthesisExtensionId;
-
-  for (int i = 0; i < 100; i++)
-    tts_platform->WillSpeakUtteranceWithVoice(&utterance, voice_data);
-  ASSERT_FALSE(IsHighQualityEnglishSpeechExtensionInstalled());
-}
-#endif  // defined(OS_CHROMEOS)
-
-}  // namespace extensions
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index b443a35..9f9f489 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -26,7 +26,6 @@
 #include "chrome/browser/extensions/api/commands/command_service.h"
 #include "chrome/browser/extensions/api/tabs/tabs_api.h"
 #include "chrome/browser/extensions/extension_web_ui.h"
-#include "chrome/browser/extensions/external_component_loader.h"
 #include "chrome/browser/external_protocol/external_protocol_handler.h"
 #include "chrome/browser/first_run/first_run.h"
 #include "chrome/browser/geolocation/geolocation_prefs.h"
@@ -344,7 +343,6 @@ void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
   chrome_browser_net::Predictor::RegisterProfilePrefs(registry);
   DownloadPrefs::RegisterProfilePrefs(registry);
   extensions::ExtensionPrefs::RegisterProfilePrefs(registry);
-  extensions::ExternalComponentLoader::RegisterProfilePrefs(registry);
   ExtensionWebUI::RegisterProfilePrefs(registry);
   HostContentSettingsMap::RegisterProfilePrefs(registry);
   IncognitoModePrefs::RegisterProfilePrefs(registry);
diff --git a/chrome/browser/resources/chromeos/speech_synthesis/manifest.json b/chrome/browser/resources/chromeos/speech_synthesis/manifest.json
index 4252fdc..26cce46 100644
--- a/chrome/browser/resources/chromeos/speech_synthesis/manifest.json
+++ b/chrome/browser/resources/chromeos/speech_synthesis/manifest.json
@@ -1,7 +1,7 @@
 {
-  "name": "Chrome OS text-to-speech component extension",
-  "version": "1.0.2",
-  "description": "Chrome OS native text-to-speech implemented using native client.",
+  "name": "Chrome OS built-in text-to-speech extension",
+  "version": "0.0.2",
+  "description": "Text-to-speech (TTS) voice extension using Native Client technology.",
   "manifest_version": 2,
   "background": {
     "scripts": [
@@ -13,8 +13,7 @@
       "voice_data_hmm_it-IT.js",
       "tts_controller.js",
       "tts_main.js"
-    ],
-    "persistent": false
+    ]
   },
   "permissions": [
     "ttsEngine",
@@ -42,13 +41,13 @@
         "event_types": [ "start", "word", "end", "error" ]
       },
       {
-        "voice_name": "Chrome OS US English Female",
+        "voice_name": "Chrome OS US English",
         "lang": "en-US",
         "gender": "female",
         "event_types": [ "start", "word", "end", "error" ]
       },
       {
-        "voice_name": "Chrome OS British English Female",
+        "voice_name": "Chrome OS British English",
         "lang": "en-GB",
         "gender": "female",
         "event_types": [ "start", "word", "end", "error" ]
diff --git a/chrome/browser/speech/tts_chromeos.cc b/chrome/browser/speech/tts_chromeos.cc
index 1c86c56..e42cb0c 100644
--- a/chrome/browser/speech/tts_chromeos.cc
+++ b/chrome/browser/speech/tts_chromeos.cc
@@ -2,27 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "base/bind_helpers.h"
-#include "base/logging.h"
-#include "base/prefs/scoped_user_pref_update.h"
-#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/speech/tts_extension_loader_chromeos.h"
 #include "chrome/browser/speech/tts_platform.h"
-#include "chrome/common/extensions/extension_constants.h"
-#include "chrome/common/pref_names.h"
-
-namespace {
-
-// Trigger installing high-quality speech after this many utterances
-// have been spoken in one session.
-const int kHighQualitySpeechUtteranceThreshold = 100;
-
-}  // anonymous namespace
 
 // Chrome OS doesn't have native TTS, instead it includes a built-in
-// component extension that provides speech synthesis. This class monitors
-// use of this component extension and triggers installing a higher-quality
-// speech synthesis extension if a certain number of utterances are spoken
-// in a single session.
+// component extension that provides speech synthesis. This class includes
+// an implementation of LoadBuiltInTtsExtension and dummy implementations of
+// everything else.
 class TtsPlatformImplChromeOs
     : public TtsPlatformImpl {
  public:
@@ -31,6 +17,10 @@ class TtsPlatformImplChromeOs
     return false;
   }
 
+  virtual bool LoadBuiltInTtsExtension(Profile* profile) OVERRIDE {
+    return TtsExtensionLoaderChromeOs::GetInstance(profile)->LoadTtsExtension();
+  }
+
   virtual bool Speak(
       int utterance_id,
       const std::string& utterance,
@@ -40,63 +30,33 @@ class TtsPlatformImplChromeOs
     return false;
   }
 
-  virtual bool StopSpeaking() OVERRIDE { return false; }
+  virtual bool StopSpeaking() OVERRIDE {
+    return false;
+  }
+
   virtual void Pause() OVERRIDE {}
+
   virtual void Resume() OVERRIDE {}
-  virtual bool IsSpeaking() OVERRIDE { return false; }
-  virtual void GetVoices(std::vector<VoiceData>* out_voices) OVERRIDE {}
 
-  virtual void WillSpeakUtteranceWithVoice(
-      const Utterance* utterance,
-      const VoiceData& voice_data) OVERRIDE;
+  virtual bool IsSpeaking() OVERRIDE {
+    return false;
+  }
+
+  virtual void GetVoices(std::vector<VoiceData>* out_voices) OVERRIDE {
+  }
 
   // Get the single instance of this class.
   static TtsPlatformImplChromeOs* GetInstance();
 
  private:
-  TtsPlatformImplChromeOs();
+  TtsPlatformImplChromeOs() {}
   virtual ~TtsPlatformImplChromeOs() {}
 
   friend struct DefaultSingletonTraits<TtsPlatformImplChromeOs>;
 
-  // A count of the number of utterances spoken for each language
-  // using the built-in speech synthesis. When enough utterances have
-  // been spoken in a single session, automatically enable install
-  // the high-quality speech synthesis extension for that language.
-  base::hash_map<std::string, int> lang_utterance_count_;
-
   DISALLOW_COPY_AND_ASSIGN(TtsPlatformImplChromeOs);
 };
 
-TtsPlatformImplChromeOs::TtsPlatformImplChromeOs() {
-}
-
-void TtsPlatformImplChromeOs::WillSpeakUtteranceWithVoice(
-    const Utterance* utterance,
-    const VoiceData& voice_data) {
-  CHECK(utterance);
-  CHECK(utterance->profile());
-
-  if (utterance->profile()->IsOffTheRecord())
-    return;
-
-  if (voice_data.extension_id != extension_misc::kSpeechSynthesisExtensionId)
-    return;
-
-  lang_utterance_count_[voice_data.lang]++;
-  if (lang_utterance_count_[voice_data.lang] !=
-          kHighQualitySpeechUtteranceThreshold) {
-    return;
-  }
-
-  // Add this language to the list that are allowed to install a
-  // component extension for high-quality speech synthesis, overriding
-  // the lower-quality one.
-  ListPrefUpdate updater(utterance->profile()->GetPrefs(),
-                         prefs::kHighQualitySpeechSynthesisLanguages);
-  updater->AppendIfNotPresent(new base::StringValue(voice_data.lang));
-}
-
 // static
 TtsPlatformImpl* TtsPlatformImpl::GetInstance() {
   return TtsPlatformImplChromeOs::GetInstance();
diff --git a/chrome/browser/speech/tts_controller.cc b/chrome/browser/speech/tts_controller.cc
index b966885..503786d 100644
--- a/chrome/browser/speech/tts_controller.cc
+++ b/chrome/browser/speech/tts_controller.cc
@@ -196,6 +196,14 @@ void TtsController::SpeakNow(Utterance* utterance) {
     if (!success)
       current_utterance_ = NULL;
 
+    // If the native voice wasn't able to process this speech, see if
+    // the browser has built-in TTS that isn't loaded yet.
+    if (!success &&
+        GetPlatformImpl()->LoadBuiltInTtsExtension(utterance->profile())) {
+      utterance_queue_.push(utterance);
+      return;
+    }
+
     if (!success) {
       utterance->OnTtsEvent(TTS_EVENT_ERROR, kInvalidCharIndex,
                             GetPlatformImpl()->error());
@@ -306,6 +314,11 @@ void TtsController::SpeakNextUtterance() {
   }
 }
 
+void TtsController::RetrySpeakingQueuedUtterances() {
+  if (current_utterance_ == NULL && !utterance_queue_.empty())
+    SpeakNextUtterance();
+}
+
 void TtsController::ClearUtteranceQueue(bool send_events) {
   while (!utterance_queue_.empty()) {
     Utterance* utterance = utterance_queue_.front();
diff --git a/chrome/browser/speech/tts_controller.h b/chrome/browser/speech/tts_controller.h
index c4329e4..c8d1c10 100644
--- a/chrome/browser/speech/tts_controller.h
+++ b/chrome/browser/speech/tts_controller.h
@@ -102,7 +102,7 @@ class Utterance {
   // when the utterance is done speaking. Before speaking this utterance,
   // its other parameters like text, rate, pitch, etc. should all be set.
   explicit Utterance(Profile* profile);
-  virtual ~Utterance();
+  ~Utterance();
 
   // Sends an event to the delegate. If the event type is TTS_EVENT_END
   // or TTS_EVENT_ERROR, deletes the utterance. If |char_index| is -1,
@@ -189,9 +189,6 @@ class Utterance {
   int id() const { return id_; }
   bool finished() const { return finished_; }
 
- protected:
-  void set_finished_for_testing(bool finished) { finished_ = finished; }
-
  private:
   // The profile that initiated this utterance.
   Profile* profile_;
@@ -286,6 +283,10 @@ class TtsController {
   // if supported, and all voices registered by extensions.
   void GetVoices(Profile* profile, std::vector<VoiceData>* out_voices);
 
+  // Called by TtsExtensionLoaderChromeOs::LoadTtsExtension when it
+  // finishes loading the built-in TTS component extension.
+  void RetrySpeakingQueuedUtterances();
+
   // Called by the extension system or platform implementation when the
   // list of voices may have changed and should be re-queried.
   void VoicesChanged();
diff --git a/chrome/browser/speech/tts_extension_loader_chromeos.cc b/chrome/browser/speech/tts_extension_loader_chromeos.cc
new file mode 100644
index 0000000..3c8f233
--- /dev/null
+++ b/chrome/browser/speech/tts_extension_loader_chromeos.cc
@@ -0,0 +1,133 @@
+// Copyright 2014 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/speech/tts_extension_loader_chromeos.h"
+
+#include "base/logging.h"
+#include "base/memory/singleton.h"
+#include "chrome/browser/extensions/component_loader.h"
+#include "chrome/browser/extensions/extension_service.h"
+#include "extensions/browser/extension_system.h"
+#include "chrome/browser/extensions/extension_system_factory.h"
+#include "chrome/browser/profiles/incognito_helpers.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/speech/extension_api/tts_engine_extension_api.h"
+#include "chrome/browser/speech/tts_controller.h"
+#include "chrome/common/extensions/extension_constants.h"
+#include "components/browser_context_keyed_service/browser_context_dependency_manager.h"
+#include "components/browser_context_keyed_service/browser_context_keyed_service.h"
+#include "components/browser_context_keyed_service/browser_context_keyed_service_factory.h"
+#include "extensions/browser/event_router.h"
+#include "grit/browser_resources.h"
+
+// Factory to load one instance of TtsExtensionLoaderChromeOs per profile.
+class TtsExtensionLoaderChromeOsFactory
+    : public BrowserContextKeyedServiceFactory {
+ public:
+  static TtsExtensionLoaderChromeOs* GetForProfile(Profile* profile) {
+    return static_cast<TtsExtensionLoaderChromeOs*>(
+        GetInstance()->GetServiceForBrowserContext(profile, true));
+  }
+
+  static TtsExtensionLoaderChromeOsFactory* GetInstance() {
+    return Singleton<TtsExtensionLoaderChromeOsFactory>::get();
+  }
+
+ private:
+  friend struct DefaultSingletonTraits<TtsExtensionLoaderChromeOsFactory>;
+
+  TtsExtensionLoaderChromeOsFactory() : BrowserContextKeyedServiceFactory(
+      "TtsExtensionLoaderChromeOs",
+      BrowserContextDependencyManager::GetInstance()) {
+    DependsOn(extensions::ExtensionSystemFactory::GetInstance());
+  }
+
+  virtual ~TtsExtensionLoaderChromeOsFactory() {}
+
+  virtual content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const OVERRIDE{
+    // If given an incognito profile (including the Chrome OS login
+    // profile), share the service with the original profile.
+    return chrome::GetBrowserContextRedirectedInIncognito(context);
+  }
+
+  virtual BrowserContextKeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* profile) const OVERRIDE {
+    return new TtsExtensionLoaderChromeOs(static_cast<Profile*>(profile));
+  }
+};
+
+TtsExtensionLoaderChromeOs*
+TtsExtensionLoaderChromeOs::GetInstance(Profile* profile) {
+  return TtsExtensionLoaderChromeOsFactory::GetInstance()
+      ->GetForProfile(profile);
+}
+
+TtsExtensionLoaderChromeOs::TtsExtensionLoaderChromeOs(
+    Profile* profile)
+    : profile_(profile) {
+  tts_state_ = IsTtsLoadedInThisProfile() ? TTS_LOADED : TTS_NOT_LOADED;
+
+  extensions::ExtensionSystem* system =
+      extensions::ExtensionSystem::Get(profile_);
+  DCHECK(system);
+  extensions::EventRouter* event_router = system->event_router();
+  DCHECK(event_router);
+  event_router->RegisterObserver(this, tts_engine_events::kOnSpeak);
+  event_router->RegisterObserver(this, tts_engine_events::kOnStop);
+}
+
+bool TtsExtensionLoaderChromeOs::LoadTtsExtension() {
+  if (tts_state_ == TTS_LOADED || tts_state_ == TTS_LOADING)
+    return false;
+
+  // Load the component extension into this profile.
+  VLOG(1) << "Loading TTS component extension.";
+  tts_state_ = TTS_LOADING;
+  ExtensionService* extension_service = profile_->GetExtensionService();
+  DCHECK(extension_service);
+  base::FilePath path =
+      base::FilePath(extension_misc::kSpeechSynthesisExtensionPath);
+  extension_service->component_loader()->Add(IDR_SPEECH_SYNTHESIS_MANIFEST,
+                                             path);
+  return true;
+}
+
+void TtsExtensionLoaderChromeOs::Shutdown() {
+  extensions::ExtensionSystem::Get(profile_)->
+      event_router()->UnregisterObserver(this);
+}
+
+bool TtsExtensionLoaderChromeOs::IsTtsLoadedInThisProfile() {
+  extensions::ExtensionSystem* system =
+      extensions::ExtensionSystem::Get(profile_);
+  DCHECK(system);
+  extensions::EventRouter* event_router = system->event_router();
+  DCHECK(event_router);
+  if (event_router->ExtensionHasEventListener(
+          extension_misc::kSpeechSynthesisExtensionId,
+          tts_engine_events::kOnSpeak) &&
+      event_router->ExtensionHasEventListener(
+          extension_misc::kSpeechSynthesisExtensionId,
+          tts_engine_events::kOnStop)) {
+    return true;
+  }
+
+  return false;
+}
+
+void TtsExtensionLoaderChromeOs::OnListenerAdded(
+    const extensions::EventListenerInfo& details) {
+  if (details.extension_id != extension_misc::kSpeechSynthesisExtensionId)
+    return;
+
+  if (!IsTtsLoadedInThisProfile())
+    return;
+
+  if (tts_state_ == TTS_LOADING) {
+    VLOG(1) << "TTS component extension loaded, retrying queued utterances.";
+    tts_state_ = TTS_LOADED;
+    TtsController::GetInstance()->RetrySpeakingQueuedUtterances();
+  }
+}
diff --git a/chrome/browser/speech/tts_extension_loader_chromeos.h b/chrome/browser/speech/tts_extension_loader_chromeos.h
new file mode 100644
index 0000000..6485042
--- /dev/null
+++ b/chrome/browser/speech/tts_extension_loader_chromeos.h
@@ -0,0 +1,56 @@
+// Copyright 2014 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.
+
+#ifndef CHROME_BROWSER_SPEECH_TTS_EXTENSION_LOADER_CHROMEOS_H_
+#define CHROME_BROWSER_SPEECH_TTS_EXTENSION_LOADER_CHROMEOS_H_
+
+#include "components/browser_context_keyed_service/browser_context_keyed_service.h"
+#include "extensions/browser/event_router.h"
+
+class Profile;
+
+// Profile-keyed class that loads a built-in TTS component extension
+// into a given profile on Chrome OS.
+class TtsExtensionLoaderChromeOs
+    : public BrowserContextKeyedService,
+      public extensions::EventRouter::Observer {
+ public:
+  static TtsExtensionLoaderChromeOs* GetInstance(Profile* profile);
+
+  // Returns true if the extension was not previously loaded and is now
+  // loading. This class will call
+  // ExtensionTtsController::RetrySpeakingQueuedUtterances when the
+  // extension finishes loading.
+  bool LoadTtsExtension();
+
+  // Implementation of BrowserContextKeyedService.
+  virtual void Shutdown() OVERRIDE;
+
+  // Implementation of extensions::EventRouter::Observer.
+  virtual void OnListenerAdded(const extensions::EventListenerInfo& details)
+      OVERRIDE;
+
+ private:
+  // The state of TTS for this profile.
+  enum TtsState {
+    TTS_NOT_LOADED,
+    TTS_LOAD_REQUESTED,
+    TTS_LOADING,
+    TTS_LOADED
+  };
+
+  explicit TtsExtensionLoaderChromeOs(Profile* profile);
+  virtual ~TtsExtensionLoaderChromeOs() {}
+
+  bool IsTtsLoadedInThisProfile();
+
+  Profile* profile_;
+  TtsState tts_state_;
+
+  friend class TtsExtensionLoaderChromeOsFactory;
+
+  DISALLOW_COPY_AND_ASSIGN(TtsExtensionLoaderChromeOs);
+};
+
+#endif  // CHROME_BROWSER_SPEECH_TTS_EXTENSION_LOADER_CHROMEOS_H_
diff --git a/chrome/browser/speech/tts_platform.cc b/chrome/browser/speech/tts_platform.cc
index 3942eff..482f041 100644
--- a/chrome/browser/speech/tts_platform.cc
+++ b/chrome/browser/speech/tts_platform.cc
@@ -6,6 +6,10 @@
 
 #include <string>
 
+bool TtsPlatformImpl::LoadBuiltInTtsExtension(Profile* profile) {
+  return false;
+}
+
 std::string TtsPlatformImpl::error() {
   return error_;
 }
diff --git a/chrome/browser/speech/tts_platform.h b/chrome/browser/speech/tts_platform.h
index bce9693..e396b7f 100644
--- a/chrome/browser/speech/tts_platform.h
+++ b/chrome/browser/speech/tts_platform.h
@@ -18,6 +18,13 @@ class TtsPlatformImpl {
   // Returns true if this platform implementation is supported and available.
   virtual bool PlatformImplAvailable() = 0;
 
+  // Some platforms may provide a built-in TTS extension. Returns true
+  // if the extension was not previously loaded and is now loading, and
+  // false if it's already loaded or if there's no extension to load.
+  // Will call TtsController::RetrySpeakingQueuedUtterances when
+  // the extension finishes loading.
+  virtual bool LoadBuiltInTtsExtension(Profile* profile);
+
   // Speak the given utterance with the given parameters if possible,
   // and return true on success. Utterance will always be nonempty.
   // If rate, pitch, or volume are -1.0, they will be ignored.
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 7d69f4f..fcf6b46 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -2101,6 +2101,8 @@
         'browser/speech/tts_chromeos.cc',
         'browser/speech/tts_controller.cc',
         'browser/speech/tts_controller.h',
+        'browser/speech/tts_extension_loader_chromeos.cc',
+        'browser/speech/tts_extension_loader_chromeos.h',
         'browser/speech/tts_linux.cc',
         'browser/speech/tts_mac.mm',
         'browser/speech/tts_platform.cc',
diff --git a/chrome/chrome_tests_unit.gypi b/chrome/chrome_tests_unit.gypi
index 0d38d4d..2a2a8bc 100644
--- a/chrome/chrome_tests_unit.gypi
+++ b/chrome/chrome_tests_unit.gypi
@@ -933,7 +933,6 @@
         'browser/extensions/extension_ui_unittest.cc',
         'browser/extensions/extension_warning_badge_service_unittest.cc',
         'browser/extensions/extension_warning_service_unittest.cc',
-        'browser/extensions/external_component_loader_unittest.cc',
         'browser/extensions/external_policy_loader_unittest.cc',
         'browser/extensions/external_provider_impl_unittest.cc',
         'browser/extensions/external_provider_impl_chromeos_unittest.cc',
diff --git a/chrome/common/extensions/extension_constants.cc b/chrome/common/extensions/extension_constants.cc
index 4d14663..e873e1d 100644
--- a/chrome/common/extensions/extension_constants.cc
+++ b/chrome/common/extensions/extension_constants.cc
@@ -138,8 +138,6 @@ const char kSpeechSynthesisExtensionPath[] =
     "/usr/share/chromeos-assets/speech_synthesis/patts";
 const char kSpeechSynthesisExtensionId[] =
     "gjjabgpgjpampikjhjpfhneeoapjbjaf";
-const char kHighQuality_en_US_ExtensionId[] =
-    "efdojdlmjknacnljjdedapanceanigkh";
 const char kWallpaperManagerId[] = "obklkkbkpaoaejdabbfldmcfplpdgolj";
 const char kFirstRunDialogId[] = "jdgcneonijmofocbhmijhacgchbihela";
 #else
diff --git a/chrome/common/extensions/extension_constants.h b/chrome/common/extensions/extension_constants.h
index 78e55a6..9b51634 100644
--- a/chrome/common/extensions/extension_constants.h
+++ b/chrome/common/extensions/extension_constants.h
@@ -257,9 +257,6 @@ namespace extension_misc {
   extern const char kSpeechSynthesisExtensionPath[];
   // The extension id of the speech synthesis extension.
   extern const char kSpeechSynthesisExtensionId[];
-  // The extension id of the high quality speech synthesis extension for
-  // en-US, which can be installed automatically from the web store.
-  extern const char kHighQuality_en_US_ExtensionId[];
   // The extension id of the wallpaper manager application.
   extern const char kWallpaperManagerId[];
   // The extension id of the first run dialog application.
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index e0645b3..368d6a8 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -880,11 +880,6 @@ const char kMultiProfileNotificationDismissed[] =
 // for more details of the valid values.
 const char kMultiProfileUserBehavior[] = "settings.multiprofile_user_behavior";
 
-// List of the set of language codes for which high quality local speech
-// synthesis has been enabled.
-const char kHighQualitySpeechSynthesisLanguages[] =
-    "settings.speech_synthesis.high_quality_languages";
-
 // A boolean preference indicating whether user has seen first-run tutorial
 // already.
 const char kFirstRunTutorialShown[] = "settings.first_run_tutorial_shown";
diff --git a/chrome/common/pref_names.h b/chrome/common/pref_names.h
index d0846d1..5d1eb3b 100644
--- a/chrome/common/pref_names.h
+++ b/chrome/common/pref_names.h
@@ -276,7 +276,6 @@ extern const char kMultiProfileNeverShowIntro[];
 extern const char kMultiProfileWarningShowDismissed[];
 extern const char kMultiProfileNotificationDismissed[];
 extern const char kMultiProfileUserBehavior[];
-extern const char kHighQualitySpeechSynthesisLanguages[];
 extern const char kFirstRunTutorialShown[];
 extern const char kSAMLOfflineSigninTimeLimit[];
 extern const char kSAMLLastGAIASignInTime[];