media: Add support for playback of VP8 Alpha video streams

media/base/video_util.h

Index: media/base/video_util.h
diff --git a/media/base/video_util.h b/media/base/video_util.h
index 27156fab7ab39e8c137a500487535c214699b660..05e5927ec6bb7679efe969a20994b78425b7a0e7 100644
--- a/media/base/video_util.h
+++ b/media/base/video_util.h
@@ -19,7 +19,7 @@ MEDIA_EXPORT gfx::Size GetNaturalSize(const gfx::Size& visible_size,
                                       int aspect_ratio_numerator,
                                       int aspect_ratio_denominator);
 
-// Copies a plane of YUV source into a VideoFrame object, taking into account
+// Copies a plane of YUV(A) source into a VideoFrame object, taking into account
 // source and destinations dimensions.
 //
 // NOTE: rows is *not* the same as height!
@@ -29,8 +29,14 @@ MEDIA_EXPORT void CopyUPlane(const uint8* source, int stride, int rows,
                              VideoFrame* frame);
 MEDIA_EXPORT void CopyVPlane(const uint8* source, int stride, int rows,
                              VideoFrame* frame);
+MEDIA_EXPORT void CopyAPlane(const uint8* source, int stride, int rows,
+                             VideoFrame* frame);
+
+// Sets alpha plane values to be completely opaque (all 255's).
+MEDIA_EXPORT void MakeOpaqueAPlane(int stride, int rows, VideoFrame* frame);
+
 // |plane| is one of VideoFrame::kYPlane, VideoFrame::kUPlane,
-// or VideoFrame::kVPlane.
+// VideoFrame::kVPlane or VideoFrame::kAPlane
 MEDIA_EXPORT void CopyPlane(size_t plane, const uint8* source, int stride,
                             int rows, VideoFrame* frame);