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

cc/test/solid_color_content_layer_client.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/test/solid_color_content_layer_client.h"
 
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/rect_f.h"
 
 namespace cc {
 
 void SolidColorContentLayerClient::PaintContents(
-    SkCanvas* canvas, gfx::Rect rect, gfx::RectF* opaque_rect) {
+    SkCanvas* canvas, const gfx::Rect& rect, gfx::RectF* opaque_rect) {
   SkPaint paint;
   paint.setStyle(SkPaint::kFill_Style);
   paint.setColor(color_);
 
   canvas->clear(SK_ColorTRANSPARENT);
   canvas->drawRect(
       SkRect::MakeXYWH(rect.x(), rect.y(), rect.width(), rect.height()),
       paint);
 
   if (SkColorGetA(color_) == 255)
     *opaque_rect = rect;
 }
 
 }  // namespace cc