Support onvoiceschanged for extension-based tts engines.

chrome/browser/speech/extension_api/tts_engine_extension_observer.cc

+// 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/extension_api/tts_engine_extension_observer.h"
+
+#include "base/logging.h"
+#include "base/memory/singleton.h"
+#include "chrome/browser/extensions/extension_service.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 "components/keyed_service/content/browser_context_dependency_manager.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "extensions/browser/event_router.h"
+#include "extensions/browser/extension_system.h"
+#include "grit/browser_resources.h"
+
+// Factory to load one instance of TtsExtensionLoaderChromeOs per profile.
+class TtsEngineExtensionObserverFactory
+    : public BrowserContextKeyedServiceFactory {
+ public:
+  static TtsEngineExtensionObserver* GetForProfile(Profile* profile) {
+    return static_cast<TtsEngineExtensionObserver*>(
+        GetInstance()->GetServiceForBrowserContext(profile, true));
+  }
+
+  static TtsEngineExtensionObserverFactory* GetInstance() {
+    return Singleton<TtsEngineExtensionObserverFactory>::get();
+  }
+
+ private:
+  friend struct DefaultSingletonTraits<TtsEngineExtensionObserverFactory>;
+
+  TtsEngineExtensionObserverFactory()
+      : BrowserContextKeyedServiceFactory(
+            "TtsEngineExtensionObserver",
+            BrowserContextDependencyManager::GetInstance()) {
+    DependsOn(extensions::ExtensionSystemFactory::GetInstance());
+  }
+
+  virtual ~TtsEngineExtensionObserverFactory() {}
+
+  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 KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* profile) const OVERRIDE {
+    return new TtsEngineExtensionObserver(static_cast<Profile*>(profile));
+  }
+};
+
+TtsEngineExtensionObserver* TtsEngineExtensionObserver::GetInstance(
+    Profile* profile) {
+  return TtsEngineExtensionObserverFactory::GetInstance()->GetForProfile(
+      profile);
+}
+
+TtsEngineExtensionObserver::TtsEngineExtensionObserver(Profile* profile)
+    : extension_registry_observer_(this),
+      profile_(profile),
+      saw_tts_engine_added_(false) {
+  extension_registry_observer_.Add(
+      extensions::ExtensionRegistry::Get(profile_));
+
+  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);
+}
+
+TtsEngineExtensionObserver::~TtsEngineExtensionObserver() {
+}
+
+bool TtsEngineExtensionObserver::SawExtensionLoad(
+    const std::string& extension_id,
+    bool update) {
+  bool previously_loaded =
+      engine_extension_ids_.find(extension_id) != engine_extension_ids_.end();
+
+  if (update)
+    engine_extension_ids_.insert(extension_id);
+
+  return previously_loaded;
+}
+
+void TtsEngineExtensionObserver::Shutdown() {
+  extensions::EventRouter::Get(profile_)->UnregisterObserver(this);
+}
+
+bool TtsEngineExtensionObserver::IsLoadedTtsEngine(
+    const std::string& extension_id) {
+  extensions::ExtensionSystem* system =
+      extensions::ExtensionSystem::Get(profile_);
+  DCHECK(system);
+  extensions::EventRouter* event_router = system->event_router();
+  DCHECK(event_router);
+  if (event_router->ExtensionHasEventListener(extension_id,
+                                              tts_engine_events::kOnSpeak) &&
+      event_router->ExtensionHasEventListener(extension_id,
+                                              tts_engine_events::kOnStop)) {
+    return true;
+  }
+
+  return false;
+}
+
+void TtsEngineExtensionObserver::OnListenerAdded(
+    const extensions::EventListenerInfo& details) {
+  if (!IsLoadedTtsEngine(details.extension_id))
+    return;
+
+  if (!saw_tts_engine_added_) {
+    saw_tts_engine_added_ = true;
+    TtsController::GetInstance()->RetrySpeakingQueuedUtterances();
+  }
+
+  TtsController::GetInstance()->VoicesChanged();
+  engine_extension_ids_.insert(details.extension_id);
+}
+
+void TtsEngineExtensionObserver::OnExtensionUnloaded(
+    content::BrowserContext* browser_context,
+    const extensions::Extension* extension,
+    extensions::UnloadedExtensionInfo::Reason reason) {
+  if (engine_extension_ids_.find(extension->id()) !=
+      engine_extension_ids_.end()) {
+    engine_extension_ids_.erase(extension->id());
+    TtsController::GetInstance()->VoicesChanged();
+  }
+}