Simplify VideoDecodeEngine interface by making everything synchronous.

Although I plan to remove VideoDecodeEngine entirely it requires detangling some of the code first.

Other noteworthy changes:
  - It's no longer valid to call VideoFrameReady(NULL), instead FFmpegVideoDecoder will raise an error the moment it finds one
  - Buffer recycling has been vanquished (for now), with video frames always allocated in the decoder
  - Produce/ConsumeVideoFrame() has been replaced by Read()
  - Video decode byte statistics are only updated if more than 0 bytes were decoded
  - FFmpegVideoDecodeEngine no longer attempts to preroll

Review URL: http://codereview.chromium.org/8417019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@108612 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 19 insertions, 30 deletions

diff --git a/media/base/filters.h b/media/base/filters.h
index 1624a60..e464202 100644
--- a/media/base/filters.h
+++ b/media/base/filters.h
@@ -164,22 +164,20 @@ class MEDIA_EXPORT VideoDecoder : public Filter {
   // Initialize a VideoDecoder with the given DemuxerStream, executing the
   // callback upon completion.
   // stats_callback is used to update global pipeline statistics.
+  //
+  // TODO(scherkus): switch to PipelineStatus callback.
   virtual void Initialize(DemuxerStream* stream, const base::Closure& callback,
                           const StatisticsCallback& stats_callback) = 0;
 
-  // Renderer provides an output buffer for Decoder to write to. These buffers
-  // will be recycled to renderer via the permanent callback.
+  // Request a frame to be decoded and returned via the provided callback.
+  // Only one read may be in flight at any given time.
   //
-  // We could also pass empty pointer here to let decoder provide buffers pool.
-  virtual void ProduceVideoFrame(scoped_refptr<VideoFrame> frame) = 0;
-
-  // Installs a permanent callback for passing decoded video output.
+  // Implementations guarantee that the callback will not be called from within
+  // this method.
   //
-  // A NULL frame represents a decoding error.
-  typedef base::Callback<void(scoped_refptr<VideoFrame>)> ConsumeVideoFrameCB;
-  void set_consume_video_frame_callback(const ConsumeVideoFrameCB& callback) {
-    consume_video_frame_callback_ = callback;
-  }
+  // Frames will be non-NULL yet may be end of stream frames.
+  typedef base::Callback<void(scoped_refptr<VideoFrame>)> ReadCB;
+  virtual void Read(const ReadCB& callback) = 0;
 
   // Returns the natural width and height of decoded video in pixels.
   //
@@ -188,22 +186,11 @@ class MEDIA_EXPORT VideoDecoder : public Filter {
   //
   // TODO(scherkus): why not rely on prerolling and decoding a single frame to
   // get dimensions?
-  virtual gfx::Size natural_size() = 0;
+  virtual const gfx::Size& natural_size() = 0;
 
  protected:
-  // Executes the permanent callback to pass off decoded video.
-  //
-  // TODO(scherkus): name this ConsumeVideoFrame() once we fix the TODO in
-  // VideoDecodeEngine::EventHandler to remove ConsumeVideoFrame() from there.
-  void VideoFrameReady(scoped_refptr<VideoFrame> frame) {
-    consume_video_frame_callback_.Run(frame);
-  }
-
   VideoDecoder();
   virtual ~VideoDecoder();
-
- private:
-  ConsumeVideoFrameCB consume_video_frame_callback_;
 };
 
 
@@ -212,6 +199,8 @@ class MEDIA_EXPORT AudioDecoder : public Filter {
   // Initialize a AudioDecoder with the given DemuxerStream, executing the
   // callback upon completion.
   // stats_callback is used to update global pipeline statistics.
+  //
+  // TODO(scherkus): switch to PipelineStatus callback.
   virtual void Initialize(DemuxerStream* stream, const base::Closure& callback,
                           const StatisticsCallback& stats_callback) = 0;
 
diff --git a/media/base/mock_filters.h b/media/base/mock_filters.h
index 8199b88..841629d 100644
--- a/media/base/mock_filters.h
+++ b/media/base/mock_filters.h
@@ -187,12 +187,8 @@ class MockVideoDecoder : public VideoDecoder {
   MOCK_METHOD3(Initialize, void(DemuxerStream* stream,
                                 const base::Closure& callback,
                                 const StatisticsCallback& stats_callback));
-  MOCK_METHOD1(ProduceVideoFrame, void(scoped_refptr<VideoFrame>));
-  MOCK_METHOD0(natural_size, gfx::Size());
-
-  void VideoFrameReadyForTest(scoped_refptr<VideoFrame> frame) {
-    VideoDecoder::VideoFrameReady(frame);
-  }
+  MOCK_METHOD1(Read, void(const ReadCB& callback));
+  MOCK_METHOD0(natural_size, const gfx::Size&());
 
  protected:
   virtual ~MockVideoDecoder();
diff --git a/media/base/video_decoder_config.cc b/media/base/video_decoder_config.cc
index d055f49..6a7add8 100644
--- a/media/base/video_decoder_config.cc
+++ b/media/base/video_decoder_config.cc
@@ -7,6 +7,7 @@
 #include <cmath>
 
 #include "base/logging.h"
+#include "media/base/limits.h"
 
 namespace media {
 
@@ -90,7 +91,10 @@ bool VideoDecoderConfig::IsValidConfig() const {
       frame_rate_numerator_ > 0 &&
       frame_rate_denominator_ > 0 &&
       aspect_ratio_numerator_ > 0 &&
-      aspect_ratio_denominator_ > 0;
+      aspect_ratio_denominator_ > 0 &&
+      natural_size_.width() <= Limits::kMaxDimension &&
+      natural_size_.height() <= Limits::kMaxDimension &&
+      natural_size_.GetArea() <= Limits::kMaxCanvas;
 }
 
 VideoCodec VideoDecoderConfig::codec() const {