cc: Don't pass simple well-defined classes by reference.

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 "base/bind.h"
 #include "base/command_line.h"
@@ skipping 543 matching lines @@
 
 void LayerTreeHost::SetNeedsFullTreeSync() {
   needs_full_tree_sync_ = true;
   SetNeedsCommit();
 }
 
 void LayerTreeHost::SetNeedsRedraw() {
   SetNeedsRedrawRect(gfx::Rect(device_viewport_size_));
 }
 
-void LayerTreeHost::SetNeedsRedrawRect(const gfx::Rect& damage_rect) {
+void LayerTreeHost::SetNeedsRedrawRect(gfx::Rect damage_rect) {
   proxy_->SetNeedsRedraw(damage_rect);
   if (!proxy_->ImplThread())
     client_->ScheduleComposite();
 }
 
 bool LayerTreeHost::CommitRequested() const {
   return proxy_->CommitRequested();
 }
 
 void LayerTreeHost::SetAnimationEvents(scoped_ptr<AnimationEventsVector> events,
@@ skipping 520 matching lines @@
     bool start_ready_animations = true;
     (*iter).second->UpdateState(start_ready_animations, NULL);
   }
 }
 
 skia::RefPtr<SkPicture> LayerTreeHost::CapturePicture() {
   return proxy_->CapturePicture();
 }
 
 }  // namespace cc