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

cc/trees/layer_tree_host.cc

 // Copyright 2011 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/trees/layer_tree_host.h"
 
 #include <algorithm>
 #include <stack>
 #include <string>
 
@@ skipping 453 matching lines @@
   DCHECK(proxy_->IsMainThread());
 
   if (output_surface_lost_)
     return;
 
   num_failed_recreate_attempts_ = 0;
   output_surface_lost_ = true;
   SetNeedsCommit();
 }
 
-bool LayerTreeHost::CompositeAndReadback(void* pixels,
-                                         gfx::Rect rect_in_device_viewport) {
+bool LayerTreeHost::CompositeAndReadback(
+    void* pixels,
+    const gfx::Rect& rect_in_device_viewport) {
   trigger_idle_updates_ = false;
   bool ret = proxy_->CompositeAndReadback(pixels, rect_in_device_viewport);
   trigger_idle_updates_ = true;
   return ret;
 }
 
 void LayerTreeHost::FinishAllRendering() {
   proxy_->FinishAllRendering();
 }
 
@@ skipping 48 matching lines @@
 
 void LayerTreeHost::SetNeedsFullTreeSync() {
   needs_full_tree_sync_ = true;
   SetNeedsCommit();
 }
 
 void LayerTreeHost::SetNeedsRedraw() {
   SetNeedsRedrawRect(gfx::Rect(device_viewport_size_));
 }
 
-void LayerTreeHost::SetNeedsRedrawRect(gfx::Rect damage_rect) {
+void LayerTreeHost::SetNeedsRedrawRect(const gfx::Rect& damage_rect) {
   proxy_->SetNeedsRedraw(damage_rect);
 }
 
 bool LayerTreeHost::CommitRequested() const {
   return proxy_->CommitRequested();
 }
 
 bool LayerTreeHost::BeginMainFrameRequested() const {
   return proxy_->BeginMainFrameRequested();
 }
@@ skipping 710 matching lines @@
   swap_promise_list_.push_back(swap_promise.Pass());
 }
 
 void LayerTreeHost::BreakSwapPromises(SwapPromise::DidNotSwapReason reason) {
   for (size_t i = 0; i < swap_promise_list_.size(); i++)
     swap_promise_list_[i]->DidNotSwap(reason);
   swap_promise_list_.clear();
 }
 
 }  // namespace cc