Add default impl for DemuxerStream::EnableBitstreamConverter().

Most DemuxerStream implementation doesn't need this method. Provide an empty default implementation in the base class so that subclass doesn't need to override it.

TBR=gunsch@chromium.org

Review URL: https://codereview.chromium.org/560563002

Cr-Commit-Position: refs/heads/master@{#294102}

chromecast/media/cma/filters/demuxer_stream_adapter_unittest.cc

@@ -48,7 +48,6 @@ class DummyDemuxerStream : public ::media::DemuxerStream {
   virtual ::media::AudioDecoderConfig audio_decoder_config() OVERRIDE;
   virtual ::media::VideoDecoderConfig video_decoder_config() OVERRIDE;
   virtual Type type() OVERRIDE;
-  virtual void EnableBitstreamConverter() OVERRIDE;
   virtual bool SupportsConfigChanges() OVERRIDE;
   virtual ::media::VideoRotation video_rotation() OVERRIDE;
 
@@ -123,9 +122,6 @@ void DummyDemuxerStream::Read(const ReadCB& read_cb) {
   return VIDEO;
 }
 
-void DummyDemuxerStream::EnableBitstreamConverter() {
-}
-
 bool DummyDemuxerStream::SupportsConfigChanges() {
   return true;
 }

media/base/demuxer_stream.cc

@@ -8,4 +8,8 @@ namespace media {
 
 DemuxerStream::~DemuxerStream() {}
 
+// Most DemuxerStream implementations don't need to convert bit stream.
+// Do nothing by default.
+void DemuxerStream::EnableBitstreamConverter() {}
+
 }  // namespace media

media/base/demuxer_stream.h

@@ -69,7 +69,7 @@ class MEDIA_EXPORT DemuxerStream {
   // Returns the type of stream.
   virtual Type type() = 0;
 
-  virtual void EnableBitstreamConverter() = 0;
+  virtual void EnableBitstreamConverter();
 
   // Whether or not this DemuxerStream allows midstream configuration changes.
   //

media/filters/chunk_demuxer.cc

@@ -933,8 +933,6 @@ void ChunkDemuxerStream::Read(const ReadCB& read_cb) {
 
 DemuxerStream::Type ChunkDemuxerStream::type() { return type_; }
 
-void ChunkDemuxerStream::EnableBitstreamConverter() {}
-
 AudioDecoderConfig ChunkDemuxerStream::audio_decoder_config() {
   CHECK_EQ(type_, AUDIO);
   base::AutoLock auto_lock(lock_);

media/filters/chunk_demuxer.h

@@ -82,7 +82,6 @@ class MEDIA_EXPORT ChunkDemuxerStream : public DemuxerStream {
   // DemuxerStream methods.
   virtual void Read(const ReadCB& read_cb) OVERRIDE;
   virtual Type type() OVERRIDE;
-  virtual void EnableBitstreamConverter() OVERRIDE;
   virtual AudioDecoderConfig audio_decoder_config() OVERRIDE;
   virtual VideoDecoderConfig video_decoder_config() OVERRIDE;
   virtual bool SupportsConfigChanges() OVERRIDE;

media/filters/fake_demuxer_stream.cc

@@ -89,10 +89,6 @@ DemuxerStream::Type FakeDemuxerStream::type() {
   return VIDEO;
 }
 
-void FakeDemuxerStream::EnableBitstreamConverter() {
-  DCHECK(task_runner_->BelongsToCurrentThread());
-}
-
 bool FakeDemuxerStream::SupportsConfigChanges() {
   return config_changes_;
 }

media/filters/fake_demuxer_stream.h

@@ -32,7 +32,6 @@ class FakeDemuxerStream : public DemuxerStream {
   virtual AudioDecoderConfig audio_decoder_config() OVERRIDE;
   virtual VideoDecoderConfig video_decoder_config() OVERRIDE;
   virtual Type type() OVERRIDE;
-  virtual void EnableBitstreamConverter() OVERRIDE;
   virtual bool SupportsConfigChanges() OVERRIDE;
   virtual VideoRotation video_rotation() OVERRIDE;