Decoders now use standard callback mechanism for Reads. Removed Assignable<> template.

Also includes an update that should provide more accurate timing from the audio renderer.
Review URL: http://codereview.chromium.org/55031

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@12796 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 12 insertions, 69 deletions

diff --git a/media/base/buffers.h b/media/base/buffers.h
index 901a8a2..d600289 100644
--- a/media/base/buffers.h
+++ b/media/base/buffers.h
@@ -177,60 +177,6 @@ class VideoFrame : public StreamSample {
   virtual void Unlock() = 0;
 };
 
-
-// An interface for receiving the results of an asynchronous read.  Downstream
-// filters typically implement this interface or use AssignableBuffer and
-// provide it to upstream filters as a read request.  When the upstream filter
-// has completed the read, they call SetBuffer/OnAssignment to notify the
-// downstream filter.
-//
-// TODO(scherkus): rethink the Assignable interface -- it's a bit kludgy.
-template <class BufferType>
-class Assignable
-    : public base::RefCountedThreadSafe< Assignable<BufferType> > {
- public:
-  // Assigns a buffer to the owner.
-  virtual void SetBuffer(BufferType* buffer) = 0;
-
-  // Notifies the owner that an assignment has been completed.
-  virtual void OnAssignment() = 0;
-
-  // TODO(scherkus): figure out a solution to friending a template.
-  // See http://www.comeaucomputing.com/techtalk/templates/#friendclassT for
-  // an explanation.
-  // protected:
-  // friend class base::RefCountedThreadSafe< Assignable<class T> >;
-  virtual ~Assignable() {}
-};
-
-
-// Template for easily creating Assignable buffers.  Pass in the pointer of the
-// object to receive the OnAssignment callback.
-template <class OwnerType, class BufferType>
-class AssignableBuffer : public Assignable<BufferType> {
- public:
-  explicit AssignableBuffer(OwnerType* owner)
-      : owner_(owner),
-        buffer_(NULL) {
-    DCHECK(owner_);
-  }
-
-  // AssignableBuffer<BufferType> implementation.
-  virtual void SetBuffer(BufferType* buffer) {
-    buffer_ = buffer;
-  }
-
-  virtual void OnAssignment() {
-    owner_->OnAssignment(buffer_.get());
-  }
-
- private:
-  OwnerType* owner_;
-  scoped_refptr<BufferType> buffer_;
-
-  DISALLOW_COPY_AND_ASSIGN(AssignableBuffer);
-};
-
 }  // namespace media
 
 #endif  // MEDIA_BASE_BUFFERS_H_
diff --git a/media/base/filters.h b/media/base/filters.h
index e36d81a..6d2b17e 100644
--- a/media/base/filters.h
+++ b/media/base/filters.h
@@ -4,8 +4,7 @@
 
 // Filters are connected in a strongly typed manner, with downstream filters
 // always reading data from upstream filters.  Upstream filters have no clue
-// who is actually reading from them, and return the results via OnAssignment
-// using the AssignableInterface<SomeBufferType> interface:
+// who is actually reading from them, and return the results via callbacks.
 //
 //                         DemuxerStream(Video) <- VideoDecoder <- VideoRenderer
 // DataSource <- Demuxer <
@@ -35,7 +34,6 @@
 
 namespace media {
 
-template <class TBuffer> class Assignable;
 class Buffer;
 class Decoder;
 class DemuxerStream;
@@ -202,8 +200,8 @@ class VideoDecoder : public MediaFilter {
   // Returns the MediaFormat for this filter.
   virtual const MediaFormat& media_format() = 0;
 
-  // Schedules a read and takes ownership of the given buffer.
-  virtual void Read(Assignable<VideoFrame>* video_frame) = 0;
+  // Schedules a read.  Decoder takes ownership of the callback.
+  virtual void Read(Callback1<VideoFrame*>::Type* read_callback) = 0;
 };
 
 
@@ -223,8 +221,8 @@ class AudioDecoder : public MediaFilter {
   // Returns the MediaFormat for this filter.
   virtual const MediaFormat& media_format() = 0;
 
-  // Schedules a read and takes ownership of the given buffer.
-  virtual void Read(Assignable<Buffer>* buffer) = 0;
+  // Schedules a read.  Decoder takes ownership of the callback.
+  virtual void Read(Callback1<Buffer*>::Type* read_callbasck) = 0;
 };
 
 
diff --git a/media/base/mock_media_filters.h b/media/base/mock_media_filters.h
index 1f7af93..fef7938 100644
--- a/media/base/mock_media_filters.h
+++ b/media/base/mock_media_filters.h
@@ -321,7 +321,7 @@ class MockAudioDecoder : public AudioDecoder {
     return media_format_;
   }
 
-  virtual void Read(Assignable<Buffer>* buffer) {
+  virtual void Read(Callback1<Buffer*>::Type* callback) {
     // TODO(ralphl): implement mock read.
     NOTREACHED();
   }
@@ -429,15 +429,16 @@ class MockVideoDecoder : public VideoDecoder {
     return media_format_;
   }
 
-  virtual void Read(Assignable<VideoFrame>* buffer) {
-    buffer->AddRef();
-    host_->PostTask(NewRunnableMethod(this, &MockVideoDecoder::DoRead, buffer));
+  virtual void Read(Callback1<VideoFrame*>::Type* callback) {
+    host_->PostTask(NewRunnableMethod(
+        this, &MockVideoDecoder::DoRead, callback));
   }
 
  private:
   virtual ~MockVideoDecoder() {}
 
-  void DoRead(Assignable<VideoFrame>* buffer) {
+  void DoRead(Callback1<VideoFrame*>::Type* callback) {
+    scoped_ptr<Callback1<VideoFrame*>::Type> scoped_callback(callback);
     if (mock_frame_time_ < config_->media_duration) {
       // TODO(ralphl): Mock video decoder only works with YV12.  Implement other
       // formats as needed.
@@ -459,11 +460,9 @@ class MockVideoDecoder : public VideoDecoder {
         }
         InitializeYV12Frame(frame, (mock_frame_time_.InSecondsF() /
                                     config_->media_duration.InSecondsF()));
-        buffer->SetBuffer(frame);
-        buffer->OnAssignment();
+        callback->Run(frame);
       }
     }
-    buffer->Release();
   }
 
   MediaFormat media_format_;