Implement native speech recognition for the launcher.

chrome/browser/ui/app_list/speech_recognizer.h

+// 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_UI_APP_LIST_SPEECH_RECOGNIZER_H_
+#define CHROME_BROWSER_UI_APP_LIST_SPEECH_RECOGNIZER_H_
+
+#include <string>
+
+#include "base/memory/weak_ptr.h"
+#include "base/timer/timer.h"
+#include "content/public/browser/speech_recognition_event_listener.h"
+#include "net/url_request/url_request_context_getter.h"
+#include "ui/app_list/speech_ui_model_observer.h"
+
+namespace app_list {
+
+class SpeechRecognizerDelegate;
+class StartPageService;
+
+// SpeechRecognizer is a wrapper around the speech recognition engine that
+// simplifies its use from the UI thread. This class handles all setup/shutdown,
+// collection of results, error cases, and threading.
+class SpeechRecognizer : public base::RefCountedThreadSafe<SpeechRecognizer>,
+                         public content::SpeechRecognitionEventListener {
+ public:
+  SpeechRecognizer(SpeechRecognizerDelegate* delegate,
+                   net::URLRequestContextGetter* url_request_context_getter,
+                   const std::string& locale);
+
+  // Start/stop the speech recognizer. Must be called on the UI thread.
+  void Start();
+  void Stop();
+
+ protected:
+  // Overidden from content::SpeechRecognitionEventListener:
+  // These are always called on the IO thread.
+  void OnRecognitionStart(int session_id) override;
+  void OnRecognitionEnd(int session_id) override;
+  void OnRecognitionResults(
+      int session_id,
+      const content::SpeechRecognitionResults& results) override;
+  void OnRecognitionError(
+      int session_id, const content::SpeechRecognitionError& error) override;
+  void OnSoundStart(int session_id) override;
+  void OnSoundEnd(int session_id) override;
+  void OnAudioLevelsChange(
+      int session_id, float volume, float noise_volume) override;
+  // Overridden, but with trivial implementations.

[Matt Giuca, 2014/11/03 02:35:52]

I don't think this line is necessary.

[Anand Mistry (off Chromium), 2014/11/03 06:51:56]

Removed.

+  void OnEnvironmentEstimationComplete(int session_id) override;
+  void OnAudioStart(int session_id) override;
+  void OnAudioEnd(int session_id) override;
+
+ private:
+  friend class base::RefCountedThreadSafe<SpeechRecognizer>;
+  ~SpeechRecognizer();
+
+  void StartOnIOThread(
+      int render_process_id,
+      scoped_refptr<net::URLRequestContextGetter> url_request_context_getter);
+  void StopOnIOThread();
+
+  void NotifyRecognitionStateChanged(SpeechRecognitionState new_state);
+
+  void StartSpeechTimeout();
+  void StopSpeechTimeout();
+  void SpeechTimeout();
+
+  SpeechRecognizerDelegate* delegate_;  // Not owned.
+  scoped_refptr<net::URLRequestContextGetter> url_request_context_getter_;
+  std::string locale_;
+  base::Timer speech_timeout_;
+  int session_;
+
+  base::WeakPtrFactory<SpeechRecognizer> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpeechRecognizer);
+};
+
+}  // namespace app_list
+
+#endif  // CHROME_BROWSER_UI_APP_LIST_SPEECH_RECOGNIZER_H_