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

cc/trees/layer_tree_host_pixeltest_masks.cc

Index: cc/trees/layer_tree_host_pixeltest_masks.cc
diff --git a/cc/trees/layer_tree_host_pixeltest_masks.cc b/cc/trees/layer_tree_host_pixeltest_masks.cc
index 9b386866ee3c4f67e023132aad95faf6a69804c7..5d5022f6c8e4dfae0123e0026e675b6a1fb3cc79 100644
--- a/cc/trees/layer_tree_host_pixeltest_masks.cc
+++ b/cc/trees/layer_tree_host_pixeltest_masks.cc
@@ -29,7 +29,6 @@ class MaskContentLayerClient : public ContentLayerClient {
   virtual void PaintContents(
       SkCanvas* canvas,
       const gfx::Rect& rect,
-      gfx::RectF* opaque_rect,
       ContentLayerClient::GraphicsContextStatus gc_status) OVERRIDE {
     SkPaint paint;
     paint.setStyle(SkPaint::kStroke_Style);
@@ -86,7 +85,6 @@ TEST_F(LayerTreeHostMasksPixelTest, ImageMaskOfLayer) {
   MaskContentLayerClient client;
   client.PaintContents(&canvas,
                        gfx::Rect(100, 100),
-                       NULL,
                        ContentLayerClient::GRAPHICS_CONTEXT_ENABLED);
   mask->SetBitmap(bitmap);