Remove media::AudioRendererImpl::SignalEndOfStream() and some other minor cleanup.

BUG=none
TEST=none

Review URL: https://chromiumcodereview.appspot.com/10389138

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@138161 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 34 insertions, 49 deletions

diff --git a/media/filters/audio_renderer_algorithm.cc b/media/filters/audio_renderer_algorithm.cc
index 8004339..030c1ac 100644
--- a/media/filters/audio_renderer_algorithm.cc
+++ b/media/filters/audio_renderer_algorithm.cc
@@ -420,12 +420,8 @@ void AudioRendererAlgorithm::EnqueueBuffer(Buffer* buffer_in) {
     request_read_cb_.Run();
 }
 
-bool AudioRendererAlgorithm::NeedsMoreData() {
-  return needs_more_data_ || IsQueueEmpty();
-}
-
-bool AudioRendererAlgorithm::IsQueueEmpty() {
-  return audio_buffer_.forward_bytes() == 0;
+bool AudioRendererAlgorithm::CanFillBuffer() {
+  return audio_buffer_.forward_bytes() > 0 && !needs_more_data_;
 }
 
 bool AudioRendererAlgorithm::IsQueueFull() {
diff --git a/media/filters/audio_renderer_algorithm.h b/media/filters/audio_renderer_algorithm.h
index 9c0543be..933be82c 100644
--- a/media/filters/audio_renderer_algorithm.h
+++ b/media/filters/audio_renderer_algorithm.h
@@ -75,8 +75,9 @@ class MEDIA_EXPORT AudioRendererAlgorithm {
   float playback_rate() const { return playback_rate_; }
   void SetPlaybackRate(float new_rate);
 
-  // Returns whether the algorithm needs more data to continue filling buffers.
-  bool NeedsMoreData();
+  // Returns whether the algorithm has enough data at the current playback rate
+  // such that it can write data on the next call to FillBuffer().
+  bool CanFillBuffer();
 
   // Returns true if |audio_buffer_| is at or exceeds capacity.
   bool IsQueueFull();
@@ -99,9 +100,6 @@ class MEDIA_EXPORT AudioRendererAlgorithm {
   bool is_muted() { return muted_; }
 
  private:
-  // Returns true if |audio_buffer_| is empty.
-  bool IsQueueEmpty();
-
   // Fills |dest| with one frame of audio data at normal speed. Returns true if
   // a frame was rendered, false otherwise.
   bool OutputNormalPlayback(uint8* dest);
diff --git a/media/filters/audio_renderer_impl.cc b/media/filters/audio_renderer_impl.cc
index bed9a68..4f59593 100644
--- a/media/filters/audio_renderer_impl.cc
+++ b/media/filters/audio_renderer_impl.cc
@@ -199,7 +199,7 @@ void AudioRendererImpl::Initialize(const scoped_refptr<AudioDecoder>& decoder,
 
 bool AudioRendererImpl::HasEnded() {
   base::AutoLock auto_lock(lock_);
-  DCHECK(!rendered_end_of_stream_ || algorithm_->NeedsMoreData());
+  DCHECK(!rendered_end_of_stream_ || !algorithm_->CanFillBuffer());
 
   return received_end_of_stream_ && rendered_end_of_stream_;
 }
@@ -277,14 +277,6 @@ void AudioRendererImpl::DecodedAudioReady(scoped_refptr<Buffer> buffer) {
   }
 }
 
-void AudioRendererImpl::SignalEndOfStream() {
-  DCHECK(received_end_of_stream_);
-  if (!rendered_end_of_stream_) {
-    rendered_end_of_stream_ = true;
-    host()->NotifyEnded();
-  }
-}
-
 void AudioRendererImpl::ScheduleRead_Locked() {
   lock_.AssertAcquired();
   if (pending_read_ || state_ == kPaused)
@@ -406,31 +398,36 @@ uint32 AudioRendererImpl::FillBuffer(uint8* dest,
       return zeros_to_write / bytes_per_frame_;
     }
 
-    // Use three conditions to determine the end of playback:
-    // 1. Algorithm needs more audio data.
-    // 2. We've received an end of stream buffer.
-    //    (received_end_of_stream_ == true)
-    // 3. Browser process has no audio data being played.
-    //    There is no way to check that condition that would work for all
-    //    derived classes, so call virtual method that would either render
-    //    end of stream or schedule such rendering.
+    // We use the following conditions to determine end of playback:
+    //   1) Algorithm can not fill the audio callback buffer
+    //   2) We received an end of stream buffer
+    //   3) We haven't already signalled that we've ended
+    //   4) Our estimated earliest end time has expired
     //
-    // Three conditions determine when an underflow occurs:
-    // 1. Algorithm has no audio data.
-    // 2. Currently in the kPlaying state.
-    // 3. Have not received an end of stream buffer.
-    if (algorithm_->NeedsMoreData()) {
-      if (received_end_of_stream_) {
-        // TODO(enal): schedule callback instead of polling.
-        if (base::Time::Now() >= earliest_end_time_)
-          SignalEndOfStream();
-      } else if (state_ == kPlaying) {
-        state_ = kUnderflow;
-        underflow_cb = underflow_cb_;
-      }
-    } else {
-      // Otherwise fill the buffer.
+    // TODO(enal): we should replace (4) with a check that the browser has no
+    // more audio data or at least use a delayed callback.
+    //
+    // We use the following conditions to determine underflow:
+    //   1) Algorithm can not fill the audio callback buffer
+    //   2) We have NOT received an end of stream buffer
+    //   3) We are in the kPlaying state
+    //
+    // Otherwise fill the buffer with whatever data we can send to the device.
+    if (!algorithm_->CanFillBuffer() && received_end_of_stream_ &&
+        !rendered_end_of_stream_ && base::Time::Now() >= earliest_end_time_) {
+      rendered_end_of_stream_ = true;
+      host()->NotifyEnded();
+    } else if (!algorithm_->CanFillBuffer() && !received_end_of_stream_ &&
+               state_ == kPlaying) {
+      state_ = kUnderflow;
+      underflow_cb = underflow_cb_;
+    } else if (algorithm_->CanFillBuffer()) {
       frames_written = algorithm_->FillBuffer(dest, requested_frames);
+      DCHECK_GT(frames_written, 0u);
+    } else {
+      // We can't write any data this cycle. For example, we may have
+      // sent all available data to the audio device while not reaching
+      // |earliest_end_time_|.
     }
 
     // The |audio_time_buffered_| is the ending timestamp of the last frame
diff --git a/media/filters/audio_renderer_impl.h b/media/filters/audio_renderer_impl.h
index 0a6d660..b3c014f 100644
--- a/media/filters/audio_renderer_impl.h
+++ b/media/filters/audio_renderer_impl.h
@@ -85,17 +85,11 @@ class MEDIA_EXPORT AudioRendererImpl
   // should the filled buffer be played. If FillBuffer() is called as the audio
   // hardware plays the buffer, then |playback_delay| should be zero.
   //
-  // FillBuffer() calls SignalEndOfStream() when it reaches end of stream.
-  //
   // Safe to call on any thread.
   uint32 FillBuffer(uint8* dest,
                     uint32 requested_frames,
                     const base::TimeDelta& playback_delay);
 
-  // Called at the end of stream when all the hardware buffers become empty
-  // (i.e. when all the data written to the device has been played).
-  void SignalEndOfStream();
-
   // Get the playback rate of |algorithm_|.
   float GetPlaybackRate();