[#2] Pass gfx structs by const ref (gfx::Rect, gfx::RectF)

cc/trees/layer_tree_host_pixeltest_on_demand_raster.cc

 // Copyright 2013 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 "cc/layers/append_quads_data.h"
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/picture_layer.h"
 #include "cc/layers/picture_layer_impl.h"
 #include "cc/quads/draw_quad.h"
 #include "cc/test/layer_tree_pixel_test.h"
@@ skipping 46 matching lines @@
 };
 
 class BlueYellowLayerClient : public ContentLayerClient {
  public:
   explicit BlueYellowLayerClient(gfx::Rect layer_rect)
       : layer_rect_(layer_rect) {}
 
   virtual void DidChangeLayerCanUseLCDText() OVERRIDE { }
 
   virtual void PaintContents(SkCanvas* canvas,
-                             gfx::Rect clip,
+                             const gfx::Rect& clip,
                              gfx::RectF* opaque) OVERRIDE {
     *opaque = gfx::RectF(layer_rect_.width(), layer_rect_.height());
 
     SkPaint paint;
     paint.setColor(SK_ColorBLUE);
     canvas->drawRect(SkRect::MakeWH(layer_rect_.width(),
                                     layer_rect_.height() / 2),
                      paint);
 
     paint.setColor(SK_ColorYELLOW);
@@ skipping 23 matching lines @@
 
   RunPixelTest(GL_WITH_BITMAP,
                layer,
                base::FilePath(FILE_PATH_LITERAL("blue_yellow.png")));
 }
 
 }  // namespace
 }  // namespace cc
 
 #endif  // OS_ANDROID