Support (E)AC3 passthrough

media/base/audio_buffer_queue.cc

Index: media/base/audio_buffer_queue.cc
diff --git a/media/base/audio_buffer_queue.cc b/media/base/audio_buffer_queue.cc
index dfa655a3be33498c11f125d12ff32d68626cacc0..a8e1f575a20d8bfa978ea237fa84b3bafe464496 100644
--- a/media/base/audio_buffer_queue.cc
+++ b/media/base/audio_buffer_queue.cc
@@ -35,7 +35,8 @@ void AudioBufferQueue::Append(const scoped_refptr<AudioBuffer>& buffer_in) {
 int AudioBufferQueue::ReadFrames(int frames,
                                  int dest_frame_offset,
                                  AudioBus* dest) {
-  DCHECK_GE(dest->frames(), frames + dest_frame_offset);
+  if (!dest->is_raw_format())
+    DCHECK_GE(dest->frames(), frames + dest_frame_offset);
   return InternalRead(frames, true, 0, dest_frame_offset, dest);
 }
 
@@ -60,6 +61,35 @@ int AudioBufferQueue::InternalRead(int frames,
                                    int source_frame_offset,
                                    int dest_frame_offset,
                                    AudioBus* dest) {
+  if (!buffers_.size())
+    return 0;
+
+  if ((*buffers_.begin())->sample_format() == kSampleFormatRaw) {
+    DCHECK(!dest_frame_offset);
+    DCHECK(!source_frame_offset);
+
+    scoped_refptr<AudioBuffer> buffer = buffers_.front();
+    int taken = buffer->frame_count();
+
+    // if |dest| is NULL, there's no need to copy.
+    if (dest)
+      buffer->ReadFrames(buffer->frame_count(), 0, dest->data_size(), dest);
+
+    if (advance_position) {
+      // Update the appropriate values since |taken| frames have been copied
+      // out.
+      frames_ -= taken;
+      DCHECK_GE(frames_, 0);
+
+      // Remove any buffers before the current buffer as there is no going
+      // backwards.
+      buffers_.pop_front();
+      current_buffer_ = buffers_.begin();
+    }
+
+    return taken;
+  }
+
   // Counts how many frames are actually read from the buffer queue.
   int taken = 0;
   BufferQueue::iterator current_buffer = current_buffer_;