Revert to zero-initializing buffers for FFmpegVideoDecoder

media/base/video_frame.h

Index: media/base/video_frame.h
diff --git a/media/base/video_frame.h b/media/base/video_frame.h
index 80169cbe822990ca487fa5993d12bc2c5a7aa0d0..e27b2297b465c616aafc03b43ad6a0facf611df2 100644
--- a/media/base/video_frame.h
+++ b/media/base/video_frame.h
@@ -250,6 +250,10 @@ class MEDIA_EXPORT VideoFrame : public base::RefCountedThreadSafe<VideoFrame> {
   static size_t AllocationSize(VideoPixelFormat format,
                                const gfx::Size& coded_size);
 
+  // Returns the actual allocation size for a YUV frame that is created by

[DaleCurtis, 2015/08/03 21:23:25]

Why do we need these two methods again? Can we just make AllocationSize return
the right information?

[emircan, 2015/08/03 21:41:54]

Only VideoFrame::CreateFrame() uses VideoFrame::AllocateYUV() to allocate
buffers and that is not equal to AllocationSize() as some alignments and padding
takes space -exceptional case-.

FFmpegVideoDecoder allocates via VideoFrame::CreateFrame() above. It sets the
pointers to the start of the planes according to the aligned allocation[0].
However, when it calls av_buffer_create, it uses AllocationSize() which is the
packed size [1].

[0]
https://code.google.com/p/chromium/codesearch#chromium/src/media/filters/ffmp...
[1]
https://code.google.com/p/chromium/codesearch#chromium/src/media/filters/ffmp...

I tried changing av_buffer_create() parameter in [2] PatchSet#4 but the bots
didn't like it. I am also not clear why this inconsistency is is there. But
having AlignedAllocationSize() helps me to make sure to zero the whole allocated
buffer. I can use AllocationSize() instead and only zero the packed size as
well. WDYT? 

[2] https://codereview.chromium.org/1227383003

+  // CreateFrame() method.
+  static size_t AlignedAllocationSize(const scoped_refptr<VideoFrame>& frame);
+
   // Returns the plane gfx::Size (in bytes) for a plane of the given coded size
   // and format.
   static gfx::Size PlaneSize(VideoPixelFormat format,