cc: Remove the opaque rect return-parameter from ContentLayerClient.

cc/layers/picture_layer.cc

Index: cc/layers/picture_layer.cc
diff --git a/cc/layers/picture_layer.cc b/cc/layers/picture_layer.cc
index 4207aa248142ba0174101773a7b38bd89ff61af4..d175a57c799feabbdddc124e65ea4ad21cdcc47f 100644
--- a/cc/layers/picture_layer.cc
+++ b/cc/layers/picture_layer.cc
@@ -182,13 +182,11 @@ skia::RefPtr<SkPicture> PictureLayer::GetPicture() const {
 
   int width = bounds().width();
   int height = bounds().height();
-  gfx::RectF opaque;
 
   SkPictureRecorder recorder;
   SkCanvas* canvas = recorder.beginRecording(width, height, NULL, 0);
   client_->PaintContents(canvas,
                          gfx::Rect(width, height),
-                         &opaque,
                          ContentLayerClient::GRAPHICS_CONTEXT_ENABLED);
   skia::RefPtr<SkPicture> picture = skia::AdoptRef(recorder.endRecording());
   return picture;