Handle Alpha channel in Canvas capture

content/renderer/media/webmediaplayer_ms.cc

Index: content/renderer/media/webmediaplayer_ms.cc
diff --git a/content/renderer/media/webmediaplayer_ms.cc b/content/renderer/media/webmediaplayer_ms.cc
index 808593065dbd2a466d08ed29bef14716034feb8a..519ca2d7635e8a8e66dd2b816955011297b8f006 100644
--- a/content/renderer/media/webmediaplayer_ms.cc
+++ b/content/renderer/media/webmediaplayer_ms.cc
@@ -470,7 +470,7 @@ void WebMediaPlayerMS::OnFrameAvailable(
       video_weblayer_.reset(new cc_blink::WebLayerImpl(
           cc::VideoLayer::Create(cc_blink::WebLayerImpl::LayerSettings(),
                                  compositor_.get(), media::VIDEO_ROTATION_0)));
-      video_weblayer_->layer()->SetContentsOpaque(true);
+      video_weblayer_->layer()->SetContentsOpaque(false);

[mcasas, 2016/02/25 22:06:25]

SetContentsOpaque(frame->format() != media::PIXEL_FORMAT_YV12A) ?

[emircan, 2016/02/26 01:33:08]

This value is set once. Since we started switching between YV12A and I420 after
the last changes, we can no longer depend on first frame representing the whole.

       video_weblayer_->SetContentsOpaqueIsFixed(true);
       get_client()->setWebLayer(video_weblayer_.get());
     }