Introduce OutputDevice interface.

Move the SwitchOutputDevice method to it.
This will simplify the evolution of code related with
low-level audio-output-device operations.

BUG=515083

Review URL: https://codereview.chromium.org/1253183008

Cr-Commit-Position: refs/heads/master@{#341294}

12 files changed, 139 insertions, 56 deletions

diff --git a/media/base/BUILD.gn b/media/base/BUILD.gn
index bedc24f..3ff3534 100644
--- a/media/base/BUILD.gn
+++ b/media/base/BUILD.gn
@@ -129,6 +129,7 @@ source_set("base") {
     "multi_channel_resampler.h",
     "null_video_sink.cc",
     "null_video_sink.h",
+    "output_device.h",
     "pipeline.cc",
     "pipeline.h",
     "pipeline_status.h",
@@ -335,6 +336,8 @@ source_set("test_support") {
     "fake_audio_renderer_sink.h",
     "fake_demuxer_stream.cc",
     "fake_demuxer_stream.h",
+    "fake_output_device.cc",
+    "fake_output_device.h",
     "fake_text_track_stream.cc",
     "fake_text_track_stream.h",
     "gmock_callback_support.h",
diff --git a/media/base/audio_renderer_mixer.cc b/media/base/audio_renderer_mixer.cc
index 5b5fe49..984798d 100644
--- a/media/base/audio_renderer_mixer.cc
+++ b/media/base/audio_renderer_mixer.cc
@@ -71,14 +71,10 @@ void AudioRendererMixer::RemoveErrorCallback(const base::Closure& error_cb) {
   NOTREACHED();
 }
 
-void AudioRendererMixer::SwitchOutputDevice(
-    const std::string& device_id,
-    const GURL& security_origin,
-    const SwitchOutputDeviceCB& callback) {
-  DVLOG(1) << __FUNCTION__ << "(" << device_id << ", " << security_origin
-           << ")";
+OutputDevice* AudioRendererMixer::GetOutputDevice() {
+  DVLOG(1) << __FUNCTION__;
   base::AutoLock auto_lock(lock_);
-  audio_sink_->SwitchOutputDevice(device_id, security_origin, callback);
+  return audio_sink_->GetOutputDevice();
 }
 
 int AudioRendererMixer::Render(AudioBus* audio_bus,
diff --git a/media/base/audio_renderer_mixer.h b/media/base/audio_renderer_mixer.h
index dc9ab92..9bc3839 100644
--- a/media/base/audio_renderer_mixer.h
+++ b/media/base/audio_renderer_mixer.h
@@ -40,9 +40,11 @@ class MEDIA_EXPORT AudioRendererMixer
     pause_delay_ = delay;
   }
 
-  void SwitchOutputDevice(const std::string& device_id,
-                          const GURL& security_origin,
-                          const SwitchOutputDeviceCB& callback);
+  // TODO(guidou): remove this method. The output device of a mixer should
+  // never be switched, as it may result in a discrepancy between the output
+  // parameters of the new device and the output parameters with which the
+  // mixer was initialized. See crbug.com/506507
+  OutputDevice* GetOutputDevice();
 
  private:
   // AudioRendererSink::RenderCallback implementation.
diff --git a/media/base/audio_renderer_mixer_input.cc b/media/base/audio_renderer_mixer_input.cc
index 6194f21..4abec01 100644
--- a/media/base/audio_renderer_mixer_input.cc
+++ b/media/base/audio_renderer_mixer_input.cc
@@ -95,17 +95,9 @@ bool AudioRendererMixerInput::SetVolume(double volume) {
   return true;
 }
 
-void AudioRendererMixerInput::SwitchOutputDevice(
-    const std::string& device_id,
-    const GURL& security_origin,
-    const SwitchOutputDeviceCB& callback) {
-  DVLOG(1) << __FUNCTION__
-           << "(" << device_id << ", " << security_origin << ")";
-  if (mixer_) {
-    mixer_->SwitchOutputDevice(device_id, security_origin, callback);
-  } else {
-    callback.Run(SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_SUPPORTED);
-  }
+OutputDevice* AudioRendererMixerInput::GetOutputDevice() {
+  DVLOG(1) << __FUNCTION__;
+  return mixer_->GetOutputDevice();
 }
 
 double AudioRendererMixerInput::ProvideInput(AudioBus* audio_bus,
diff --git a/media/base/audio_renderer_mixer_input.h b/media/base/audio_renderer_mixer_input.h
index 06a0de1..f2b8c3e 100644
--- a/media/base/audio_renderer_mixer_input.h
+++ b/media/base/audio_renderer_mixer_input.h
@@ -33,9 +33,7 @@ class MEDIA_EXPORT AudioRendererMixerInput
   void Play() override;
   void Pause() override;
   bool SetVolume(double volume) override;
-  void SwitchOutputDevice(const std::string& device_id,
-                          const GURL& security_origin,
-                          const SwitchOutputDeviceCB& callback) override;
+  OutputDevice* GetOutputDevice() override;
   void Initialize(const AudioParameters& params,
                   AudioRendererSink::RenderCallback* renderer) override;
 
diff --git a/media/base/audio_renderer_sink.h b/media/base/audio_renderer_sink.h
index 753135d..2d1b0aa 100644
--- a/media/base/audio_renderer_sink.h
+++ b/media/base/audio_renderer_sink.h
@@ -16,6 +16,7 @@
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_bus.h"
 #include "media/base/media_export.h"
+#include "media/base/output_device.h"
 #include "url/gurl.h"
 
 namespace base {
@@ -24,8 +25,6 @@ class SingleThreadTaskRunner;
 
 namespace media {
 
-typedef base::Callback<void(SwitchOutputDeviceResult)> SwitchOutputDeviceCB;
-
 // AudioRendererSink is an interface representing the end-point for
 // rendered audio.  An implementation is expected to
 // periodically call Render() on a callback object.
@@ -67,20 +66,12 @@ class AudioRendererSink
   // Returns |true| on success.
   virtual bool SetVolume(double volume) = 0;
 
-  // Attempts to switch the audio output device.
-  // Once the attempt is finished, |callback| is invoked with the
-  // result of the operation passed as a parameter. The result is a value from
-  // the  media::SwitchOutputDeviceResult enum.
-  // There is no guarantee about the thread where |callback| will
-  // be invoked, so users are advised to use media::BindToCurrentLoop() to
-  // ensure that |callback| runs on the correct thread.
-  // Note also that copy constructors and destructors for arguments bound to
-  // |callback| may run on arbitrary threads as |callback| is moved across
-  // threads. It is advisable to bind arguments such that they are released by
-  // |callback| when it runs in order to avoid surprises.
-  virtual void SwitchOutputDevice(const std::string& device_id,
-                                  const GURL& security_origin,
-                                  const SwitchOutputDeviceCB& callback) = 0;
+  // Returns a pointer to the internal output device.
+  // This pointer is not to be owned by the caller and is valid only during
+  // the lifetime of the AudioRendererSink.
+  // It can be null, which means that access to the output device is not
+  // supported.
+  virtual OutputDevice* GetOutputDevice() = 0;
 
  protected:
   friend class base::RefCountedThreadSafe<AudioRendererSink>;
diff --git a/media/base/fake_audio_renderer_sink.cc b/media/base/fake_audio_renderer_sink.cc
index 4c4233b..d8a7262 100644
--- a/media/base/fake_audio_renderer_sink.cc
+++ b/media/base/fake_audio_renderer_sink.cc
@@ -8,13 +8,14 @@
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
+#include "media/base/fake_output_device.h"
 
 namespace media {
 
 FakeAudioRendererSink::FakeAudioRendererSink()
     : state_(kUninitialized),
-      callback_(NULL) {
-}
+      callback_(NULL),
+      output_device_(new FakeOutputDevice) {}
 
 FakeAudioRendererSink::~FakeAudioRendererSink() {
   DCHECK(!callback_);
@@ -55,11 +56,8 @@ bool FakeAudioRendererSink::SetVolume(double volume) {
   return true;
 }
 
-void FakeAudioRendererSink::SwitchOutputDevice(
-    const std::string& device_id,
-    const GURL& security_origin,
-    const SwitchOutputDeviceCB& callback) {
-  callback.Run(SWITCH_OUTPUT_DEVICE_RESULT_SUCCESS);
+OutputDevice* FakeAudioRendererSink::GetOutputDevice() {
+  return output_device_.get();
 }
 
 bool FakeAudioRendererSink::Render(AudioBus* dest, int audio_delay_milliseconds,
diff --git a/media/base/fake_audio_renderer_sink.h b/media/base/fake_audio_renderer_sink.h
index 1982ba3..0a9bd93 100644
--- a/media/base/fake_audio_renderer_sink.h
+++ b/media/base/fake_audio_renderer_sink.h
@@ -12,6 +12,8 @@
 
 namespace media {
 
+class FakeOutputDevice;
+
 class FakeAudioRendererSink : public AudioRendererSink {
  public:
   enum State {
@@ -32,9 +34,7 @@ class FakeAudioRendererSink : public AudioRendererSink {
   void Pause() override;
   void Play() override;
   bool SetVolume(double volume) override;
-  void SwitchOutputDevice(const std::string& device_id,
-                          const GURL& security_origin,
-                          const SwitchOutputDeviceCB& callback) override;
+  OutputDevice* GetOutputDevice() override;
 
   // Attempts to call Render() on the callback provided to
   // Initialize() with |dest| and |audio_delay_milliseconds|.
@@ -57,6 +57,7 @@ class FakeAudioRendererSink : public AudioRendererSink {
 
   State state_;
   RenderCallback* callback_;
+  scoped_ptr<FakeOutputDevice> output_device_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeAudioRendererSink);
 };
diff --git a/media/base/fake_output_device.cc b/media/base/fake_output_device.cc
new file mode 100644
index 0000000..4d5136b
--- /dev/null
+++ b/media/base/fake_output_device.cc
@@ -0,0 +1,21 @@
+// Copyright (c) 2015 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 "media/base/fake_output_device.h"
+
+#include "base/callback.h"
+
+namespace media {
+
+FakeOutputDevice::FakeOutputDevice() {}
+FakeOutputDevice::~FakeOutputDevice() {}
+
+void FakeOutputDevice::SwitchOutputDevice(
+    const std::string& device_id,
+    const GURL& security_origin,
+    const SwitchOutputDeviceCB& callback) {
+  callback.Run(SWITCH_OUTPUT_DEVICE_RESULT_SUCCESS);
+}
+
+}  // namespace media
diff --git a/media/base/fake_output_device.h b/media/base/fake_output_device.h
new file mode 100644
index 0000000..87d1959
--- /dev/null
+++ b/media/base/fake_output_device.h
@@ -0,0 +1,30 @@
+// Copyright (c) 2015 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 MEDIA_AUDIO_FAKE_OUTPUT_DEVICE_H_
+#define MEDIA_AUDIO_FAKE_OUTPUT_DEVICE_H_
+
+#include <string>
+
+#include "media/base/output_device.h"
+
+namespace media {
+
+class FakeOutputDevice : public OutputDevice {
+ public:
+  FakeOutputDevice();
+  ~FakeOutputDevice() override;
+
+  // OutputDevice implementation.
+  void SwitchOutputDevice(const std::string& device_id,
+                          const GURL& security_origin,
+                          const SwitchOutputDeviceCB& callback) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(FakeOutputDevice);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_FAKE_OUTPUT_DEVICE_H_
diff --git a/media/base/mock_audio_renderer_sink.h b/media/base/mock_audio_renderer_sink.h
index b813257..46589fb 100644
--- a/media/base/mock_audio_renderer_sink.h
+++ b/media/base/mock_audio_renderer_sink.h
@@ -22,12 +22,7 @@ class MockAudioRendererSink : public AudioRendererSink {
   MOCK_METHOD0(Pause, void());
   MOCK_METHOD0(Play, void());
   MOCK_METHOD1(SetVolume, bool(double volume));
-  MOCK_METHOD0(SwitchOutputDevice, void());
-  void SwitchOutputDevice(const std::string&,
-                          const GURL& security_origin,
-                          const SwitchOutputDeviceCB& callback) override {
-    SwitchOutputDevice();
-  }
+  MOCK_METHOD0(GetOutputDevice, OutputDevice*());
 
   void Initialize(const AudioParameters& params,
                   RenderCallback* renderer) override;
diff --git a/media/base/output_device.h b/media/base/output_device.h
new file mode 100644
index 0000000..c5ac791
--- /dev/null
+++ b/media/base/output_device.h
@@ -0,0 +1,56 @@
+// Copyright (c) 2015 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 MEDIA_BASE_OUTPUT_DEVICE_H_
+#define MEDIA_BASE_OUTPUT_DEVICE_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "media/audio/audio_parameters.h"
+#include "media/base/media_export.h"
+#include "url/gurl.h"
+
+namespace media {
+
+// Result of an audio output device switch operation
+enum SwitchOutputDeviceResult {
+  SWITCH_OUTPUT_DEVICE_RESULT_SUCCESS = 0,
+  SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_FOUND,
+  SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_AUTHORIZED,
+  SWITCH_OUTPUT_DEVICE_RESULT_ERROR_OBSOLETE,
+  SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_SUPPORTED,
+  SWITCH_OUTPUT_DEVICE_RESULT_LAST =
+      SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_SUPPORTED,
+};
+
+typedef base::Callback<void(SwitchOutputDeviceResult)> SwitchOutputDeviceCB;
+
+// OutputDevice is an interface that allows performing operations related
+// audio output devices.
+
+class OutputDevice {
+ public:
+  // Attempts to switch the audio output device.
+  // Once the attempt is finished, |callback| is invoked with the
+  // result of the operation passed as a parameter. The result is a value from
+  // the  media::SwitchOutputDeviceResult enum.
+  // There is no guarantee about the thread where |callback| will
+  // be invoked, so users are advised to use media::BindToCurrentLoop() to
+  // ensure that |callback| runs on the correct thread.
+  // Note also that copy constructors and destructors for arguments bound to
+  // |callback| may run on arbitrary threads as |callback| is moved across
+  // threads. It is advisable to bind arguments such that they are released by
+  // |callback| when it runs in order to avoid surprises.
+  virtual void SwitchOutputDevice(const std::string& device_id,
+                                  const GURL& security_origin,
+                                  const SwitchOutputDeviceCB& callback) = 0;
+
+ protected:
+  virtual ~OutputDevice() {}
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_OUTPUT_DEVICE_H_