Refactored TTS extension code so that the platform-specific TTS...

chrome/browser/extensions/extension_tts_api_linux.cc

+// Copyright (c) 2010 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_tts_api.h"
+
+#include "base/singleton.h"
+#include "chrome/browser/chromeos/cros/cros_library.h"
+#include "chrome/browser/chromeos/cros/speech_synthesis_library.h"
+
+namespace util = extension_tts_api_util;
+
+namespace {
+const char kNotSupportedError[] =
+    "Native speech synthesis not supported on this platform.";
+};
+
+class ExtensionTtsPlatformImplLinux : public ExtensionTtsPlatformImpl {
+ public:
+  virtual bool Speak(
+      const std::string& utterance,
+      const std::string& language,
+      const std::string& gender,
+      double rate,
+      double pitch,
+      double volume) {
+    error_ = kNotSupportedError;
+    return false;
+  }
+
+  virtual bool StopSpeaking() {
+    error_ = kNotSupportedError;
+    return false;
+  }
+
+  virtual bool IsSpeaking() {
+    error_ = kNotSupportedError;
+    return false;
+  }
+
+  // Get the single instance of this class.
+  static ExtensionTtsPlatformImplLinux* GetInstance() {
+    return ExtensionTtsPlatformImplLinux::GetInstance();
+  }
+
+ private:
+  ExtensionTtsPlatformImplLinux() {}
+  virtual ~ExtensionTtsPlatformImplLinux() {}
+
+  friend struct DefaultSingletonTraits<ExtensionTtsPlatformImplLinux>;
+
+  DISALLOW_COPY_AND_ASSIGN(ExtensionTtsPlatformImplLinux);
+};
+
+// static
+ExtensionTtsPlatformImpl* ExtensionTtsPlatformImpl::GetInstance() {
+  return ExtensionTtsPlatformImplLinux::GetInstance();
+}