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> {

[Lei Zhang, 2014/11/05 00:54:15]

Does this still need to be RefCountedThreadSafe now that it lives on a single
thread?

[Anand Mistry (off Chromium), 2014/11/05 02:58:33]

No it doesn't. Removed.

+ 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();
+
+ private:
+  friend class base::RefCountedThreadSafe<SpeechRecognizer>;
+  class EventListener;
+
+  ~SpeechRecognizer();
+
+  SpeechRecognizerDelegate* delegate_;  // Not owned.
+  scoped_refptr<EventListener> speech_event_listener_;
+
+  // Weak pointer to pass to EventListener.
+  base::WeakPtrFactory<SpeechRecognizerDelegate> delegate_weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpeechRecognizer);
+};
+
+}  // namespace app_list
+
+#endif  // CHROME_BROWSER_UI_APP_LIST_SPEECH_RECOGNIZER_H_