Support reading pixels from HW-decoded video textures into canvas/webgl.

media/base/video_frame.cc

Index: media/base/video_frame.cc
diff --git a/media/base/video_frame.cc b/media/base/video_frame.cc
index 5409e8458f247ddd038698b9cb9689178a9e01dd..7c1ea809cc1823c5ef10df0968ee68489ee3043f 100644
--- a/media/base/video_frame.cc
+++ b/media/base/video_frame.cc
@@ -61,15 +61,23 @@ scoped_refptr<VideoFrame> VideoFrame::WrapNativeTexture(
     const gfx::Size& data_size,
     const gfx::Size& natural_size,
     base::TimeDelta timestamp,
+    const ReadPixelsCB& read_pixels_cb,
     const base::Closure& no_longer_needed) {
   scoped_refptr<VideoFrame> frame(
       new VideoFrame(NATIVE_TEXTURE, data_size, natural_size, timestamp));
   frame->texture_id_ = texture_id;
   frame->texture_target_ = texture_target;
+  frame->read_pixels_cb_ = read_pixels_cb;
   frame->texture_no_longer_needed_ = no_longer_needed;
   return frame;
 }
 
+void VideoFrame::ReadPixelsFromNativeTexture(void* pixels) {
+  DCHECK_EQ(format_, NATIVE_TEXTURE);
+  if (!read_pixels_cb_.is_null())
+    read_pixels_cb_.Run(pixels);
+}
+
 // static
 scoped_refptr<VideoFrame> VideoFrame::CreateEmptyFrame() {
   return new VideoFrame(