app_shell: Do simple audio initialization.

extensions/shell/browser/shell_audio_controller_chromeos.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 EXTENSIONS_SHELL_BROWSER_SHELL_AUDIO_CONTROLLER_CHROMEOS_H_
+#define EXTENSIONS_SHELL_BROWSER_SHELL_AUDIO_CONTROLLER_CHROMEOS_H_
+
+#include "base/macros.h"
+#include "chromeos/audio/audio_devices_pref_handler.h"
+#include "chromeos/audio/cras_audio_handler.h"
+
+namespace chromeos {
+class AudioDevicesPrefHandler;
+}
+
+namespace extensions {
+
+// Ensures that the "best" input and output audio devices are always active.
+class ShellAudioController : public chromeos::CrasAudioHandler::AudioObserver {
+ public:
+  // Requests max volume for all devices and doesn't bother saving prefs.
+  class PrefHandler : public chromeos::AudioDevicesPrefHandler {
+   public:
+    PrefHandler();
+
+    // chromeos::AudioDevicesPrefHandler implementation:
+    virtual double GetOutputVolumeValue(
+        const chromeos::AudioDevice* device) OVERRIDE;
+    virtual double GetInputGainValue(
+        const chromeos::AudioDevice* device) OVERRIDE;
+    virtual void SetVolumeGainValue(const chromeos::AudioDevice& device,
+                                    double value) OVERRIDE;
+    virtual bool GetMuteValue(const chromeos::AudioDevice& device) OVERRIDE;
+    virtual void SetMuteValue(const chromeos::AudioDevice& device,
+                              bool mute_on) OVERRIDE;
+    virtual bool GetAudioCaptureAllowedValue() OVERRIDE;
+    virtual bool GetAudioOutputAllowedValue() OVERRIDE;
+    virtual void AddAudioPrefObserver(
+        chromeos::AudioPrefObserver* observer) OVERRIDE;
+    virtual void RemoveAudioPrefObserver(
+        chromeos::AudioPrefObserver* observer) OVERRIDE;
+
+   protected:
+    virtual ~PrefHandler();
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(PrefHandler);
+  };
+
+  ShellAudioController();
+  virtual ~ShellAudioController();
+
+  // chromeos::CrasAudioHandler::Observer implementation:
+  virtual void OnOutputVolumeChanged() OVERRIDE;
+  virtual void OnOutputMuteChanged() OVERRIDE;
+  virtual void OnInputGainChanged() OVERRIDE;
+  virtual void OnInputMuteChanged() OVERRIDE;
+  virtual void OnAudioNodesChanged() OVERRIDE;
+  virtual void OnActiveOutputNodeChanged() OVERRIDE;
+  virtual void OnActiveInputNodeChanged() OVERRIDE;
+
+ private:
+  // Gets the current device list from CRAS, chooses the best input and output
+  // device, and activates them if they aren't already active.
+  void ActivateDevices();
+
+  DISALLOW_COPY_AND_ASSIGN(ShellAudioController);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_SHELL_BROWSER_SHELL_AUDIO_CONTROLLER_CHROMEOS_H_