Use SkSrc_Mode in SkCanvasVideoRenderer, to prevent transparent video frames from blending with reu…

media/base/video_frame.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/base/video_frame.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 354 matching lines @@
 }
 
 // static
 scoped_refptr<VideoFrame> VideoFrame::CreateBlackFrame(const gfx::Size& size) {
   const uint8 kBlackY = 0x00;
   const uint8 kBlackUV = 0x80;
   const base::TimeDelta kZero;
   return CreateColorFrame(size, kBlackY, kBlackUV, kBlackUV, kZero);
 }
 
+// static
+scoped_refptr<VideoFrame> VideoFrame::CreateTransparentFrame(
+    const gfx::Size& size) {
+  const uint8 kBlackY = 0x00;
+  const uint8 kBlackUV = 0x00;
+  const uint8 kTransparentA = 0x00;
+  const base::TimeDelta kZero;
+  scoped_refptr<VideoFrame> frame = VideoFrame::CreateFrame(
+      VideoFrame::YV12A, size, gfx::Rect(size), size, kZero);
+  FillYUVA(frame, kBlackY, kBlackUV, kBlackUV, kTransparentA);
+  return frame;
+}
+
 #if defined(VIDEO_HOLE)
 // This block and other blocks wrapped around #if defined(VIDEO_HOLE) is not
 // maintained by the general compositor team. Please contact the following
 // people instead:
 //
 // wonsik@chromium.org
 // ycheo@chromium.org
 
 // static
 scoped_refptr<VideoFrame> VideoFrame::CreateHoleFrame(
@@ skipping 454 matching lines @@
       break;
     for (int row = 0; row < rows(plane); ++row) {
       base::MD5Update(context, base::StringPiece(
           reinterpret_cast<char*>(data(plane) + stride(plane) * row),
           row_bytes(plane)));
     }
   }
 }
 
 }  // namespace media