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

cc/trees/single_thread_proxy.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/single_thread_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "cc/base/thread.h"
 #include "cc/output/context_provider.h"
@@ skipping 210 matching lines @@
   }
   layer_tree_host_->CommitComplete();
   next_frame_is_newly_committed_frame_ = true;
 }
 
 void SingleThreadProxy::SetNeedsCommit() {
   DCHECK(Proxy::IsMainThread());
   layer_tree_host_->ScheduleComposite();
 }
 
-void SingleThreadProxy::SetNeedsRedraw(const gfx::Rect& damage_rect) {
+void SingleThreadProxy::SetNeedsRedraw(gfx::Rect damage_rect) {
   // FIXME: Once we move render_widget scheduling into this class, we can
   // treat redraw requests more efficiently than CommitAndRedraw requests.
   layer_tree_host_impl_->SetViewportDamage(damage_rect);
   SetNeedsCommit();
 }
 
 void SingleThreadProxy::OnHasPendingTreeStateChanged(bool have_pending_tree) {
   // Thread-only feature.
   NOTREACHED();
 }
@@ skipping 227 matching lines @@
 
 bool SingleThreadProxy::CommitPendingForTesting() { return false; }
 
 skia::RefPtr<SkPicture> SingleThreadProxy::CapturePicture() {
   // Impl-side painting only.
   NOTREACHED();
   return skia::RefPtr<SkPicture>();
 }
 
 }  // namespace cc