Implements AudioInputDevice API for low-latency audio input in the browser process.

Also refactors some shared audio code into audio_common.{cc,h}.

Patch by henrika@chromim.org:
http://codereview.chromium.org/6250196/

BUG=none
TEST=none

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@81315 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 85 insertions, 13 deletions

diff --git a/media/audio/audio_input_controller.cc b/media/audio/audio_input_controller.cc
index 3d58a50..311a54e 100644
--- a/media/audio/audio_input_controller.cc
+++ b/media/audio/audio_input_controller.cc
@@ -14,11 +14,13 @@ static const int kMaxInputChannels = 2;
 // static
 AudioInputController::Factory* AudioInputController::factory_ = NULL;
 
-AudioInputController::AudioInputController(EventHandler* handler)
+AudioInputController::AudioInputController(EventHandler* handler,
+                                           SyncWriter* sync_writer)
     : handler_(handler),
       stream_(NULL),
       state_(kEmpty),
-      thread_("AudioInputControllerThread") {
+      thread_("AudioInputControllerThread"),
+      sync_writer_(sync_writer) {
 }
 
 AudioInputController::~AudioInputController() {
@@ -37,7 +39,33 @@ scoped_refptr<AudioInputController> AudioInputController::Create(
   }
 
   scoped_refptr<AudioInputController> controller(new AudioInputController(
-      event_handler));
+      event_handler, NULL));
+
+  // Start the thread and post a task to create the audio input stream.
+  controller->thread_.Start();
+  controller->thread_.message_loop()->PostTask(
+      FROM_HERE,
+      NewRunnableMethod(controller.get(), &AudioInputController::DoCreate,
+                        params));
+  return controller;
+}
+
+// static
+scoped_refptr<AudioInputController> AudioInputController::CreateLowLatency(
+    EventHandler* event_handler,
+    AudioParameters params,
+    SyncWriter* sync_writer) {
+  DCHECK(sync_writer);
+
+  if (!params.IsValid() || (params.channels > kMaxInputChannels))
+    return NULL;
+
+  if (!AudioManager::GetAudioManager())
+    return NULL;
+
+  // Starts the audio controller thread.
+  scoped_refptr<AudioInputController> controller(new AudioInputController(
+      event_handler, sync_writer));
 
   // Start the thread and post a task to create the audio input stream.
   controller->thread_.Start();
@@ -126,6 +154,10 @@ void AudioInputController::DoClose() {
     stream_ = NULL;
   }
 
+  if (LowLatencyMode()) {
+    sync_writer_->Close();
+  }
+
   // Since the stream is closed at this point there's no other threads reading
   // |state_| so we don't need to lock.
   state_ = kClosed;
@@ -143,6 +175,14 @@ void AudioInputController::OnData(AudioInputStream* stream, const uint8* data,
     if (state_ != kRecording)
       return;
   }
+
+  // Use SyncSocket if we are in a low-latency mode.
+  if (LowLatencyMode()) {
+    sync_writer_->Write(data, size);
+    sync_writer_->UpdateRecordedBytes(size);
+    return;
+  }
+
   handler_->OnData(this, data, size);
 }
 
diff --git a/media/audio/audio_input_controller.h b/media/audio/audio_input_controller.h
index c630a67..b21eaba 100644
--- a/media/audio/audio_input_controller.h
+++ b/media/audio/audio_input_controller.h
@@ -34,9 +34,9 @@
 //
 namespace media {
 
-class AudioInputController :
-    public base::RefCountedThreadSafe<AudioInputController>,
-    public AudioInputStream::AudioInputCallback {
+class AudioInputController
+    : public base::RefCountedThreadSafe<AudioInputController>,
+      public AudioInputStream::AudioInputCallback {
  public:
   // An event handler that receives events from the AudioInputController. The
   // following methods are called on the audio input controller thread.
@@ -50,13 +50,30 @@ class AudioInputController :
                         uint32 size) = 0;
   };
 
+  // A synchronous writer interface used by AudioInputController for
+  // synchronous writing.
+  class SyncWriter {
+   public:
+    virtual ~SyncWriter() {}
+
+    // Notify the synchronous writer about the number of bytes in the
+    // AudioInputController which has been recorded.
+    virtual void UpdateRecordedBytes(uint32 bytes) = 0;
+
+    // Write certain amount of data from |data|. This method returns
+    // number of written bytes.
+    virtual uint32 Write(const void* data, uint32 size) = 0;
+
+    // Close this synchronous writer.
+    virtual void Close() = 0;
+  };
+
   // AudioInputController::Create uses the currently registered Factory to
   // create the AudioInputController. Factory is intended for testing.
   class Factory {
    public:
     virtual AudioInputController* Create(EventHandler* event_handler,
                                          AudioParameters params) = 0;
-
    protected:
     virtual ~Factory() {}
   };
@@ -71,6 +88,13 @@ class AudioInputController :
       EventHandler* event_handler,
       AudioParameters params);
 
+  // Factory method for creating a low latency audio stream.
+  static scoped_refptr<AudioInputController> CreateLowLatency(
+      EventHandler* event_handler,
+      AudioParameters params,
+      // External synchronous reader for audio controller.
+      SyncWriter* sync_writer);
+
   // Sets the factory used by the static method Create. AudioInputController
   // does not take ownership of |factory|. A value of NULL results in an
   // AudioInputController being created directly.
@@ -89,6 +113,8 @@ class AudioInputController :
   // will have no effect.
   virtual void Close();
 
+  bool LowLatencyMode() const { return sync_writer_ != NULL; }
+
   ///////////////////////////////////////////////////////////////////////////
   // AudioInputCallback methods.
   virtual void OnData(AudioInputStream* stream, const uint8* src, uint32 size);
@@ -105,7 +131,7 @@ class AudioInputController :
     kError
   };
 
-  AudioInputController(EventHandler* handler);
+  AudioInputController(EventHandler* handler, SyncWriter* sync_writer);
 
   // The following methods are executed on the audio controller thread.
   void DoCreate(AudioParameters params);
@@ -126,6 +152,9 @@ class AudioInputController :
   // The audio input controller thread that this object runs on.
   base::Thread thread_;
 
+  // SyncWriter is used only in low latency mode for synchronous writing.
+  SyncWriter* sync_writer_;
+
   static Factory* factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioInputController);
@@ -133,4 +162,4 @@ class AudioInputController :
 
 }  // namespace media
 
-#endif  //  MEDIA_AUDIO_AUDIO_INPUT_CONTROLLER_H_
+#endif  // MEDIA_AUDIO_AUDIO_INPUT_CONTROLLER_H_
diff --git a/media/audio/test_audio_input_controller_factory.cc b/media/audio/test_audio_input_controller_factory.cc
index 2a2f402..a31ed3d 100644
--- a/media/audio/test_audio_input_controller_factory.cc
+++ b/media/audio/test_audio_input_controller_factory.cc
@@ -8,8 +8,10 @@
 namespace media {
 
 TestAudioInputController::TestAudioInputController(
-    TestAudioInputControllerFactory* factory, EventHandler* event_handler)
-    : AudioInputController(event_handler),
+    TestAudioInputControllerFactory* factory,
+    EventHandler* event_handler,
+    SyncWriter* sync_writer)
+    : AudioInputController(event_handler, sync_writer),
       factory_(factory),
       event_handler_(event_handler) {
 }
@@ -27,7 +29,7 @@ AudioInputController* TestAudioInputControllerFactory::Create(
     AudioInputController::EventHandler* event_handler,
     AudioParameters params) {
   DCHECK(!controller_);  // Only one test instance managed at a time.
-  controller_ = new TestAudioInputController(this, event_handler);
+  controller_ = new TestAudioInputController(this, event_handler, NULL);
   return controller_;
 }
 
diff --git a/media/audio/test_audio_input_controller_factory.h b/media/audio/test_audio_input_controller_factory.h
index 3339a23..97b7201 100644
--- a/media/audio/test_audio_input_controller_factory.h
+++ b/media/audio/test_audio_input_controller_factory.h
@@ -45,7 +45,8 @@ class TestAudioInputControllerFactory;
 class TestAudioInputController : public AudioInputController {
  public:
   TestAudioInputController(TestAudioInputControllerFactory* factory,
-                           EventHandler* event_handler);
+                           EventHandler* event_handler,
+                           SyncWriter* sync_writer);
   virtual ~TestAudioInputController();
 
   // Returns the event handler installed on the AudioInputController.