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

cc/output/software_output_device.cc

Index: cc/output/software_output_device.cc
diff --git a/cc/output/software_output_device.cc b/cc/output/software_output_device.cc
index 17ef63f6d57731f26b7afe5870c59fc3e99c04a4..3e75e069f376f4ef038134e3a6806c50aad2e1d2 100644
--- a/cc/output/software_output_device.cc
+++ b/cc/output/software_output_device.cc
@@ -27,7 +27,7 @@ void SoftwareOutputDevice::Resize(gfx::Size viewport_size) {
   canvas_ = skia::AdoptRef(new SkCanvas(device_.get()));
 }
 
-SkCanvas* SoftwareOutputDevice::BeginPaint(gfx::Rect damage_rect) {
+SkCanvas* SoftwareOutputDevice::BeginPaint(const gfx::Rect& damage_rect) {
   DCHECK(device_);
   damage_rect_ = damage_rect;
   return canvas_.get();
@@ -42,14 +42,14 @@ void SoftwareOutputDevice::EndPaint(SoftwareFrameData* frame_data) {
 }
 
 void SoftwareOutputDevice::CopyToBitmap(
-    gfx::Rect rect, SkBitmap* output) {
+    const gfx::Rect& rect, SkBitmap* output) {
   DCHECK(device_);
   const SkBitmap& bitmap = device_->accessBitmap(false);
   bitmap.extractSubset(output, gfx::RectToSkIRect(rect));
 }
 
 void SoftwareOutputDevice::Scroll(
-    gfx::Vector2d delta, gfx::Rect clip_rect) {
+    gfx::Vector2d delta, const gfx::Rect& clip_rect) {
   NOTIMPLEMENTED();
 }