ui: Clean up damaged rects and clear them after painting.

ui/compositor/compositor.cc

 // Copyright (c) 2012 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 "ui/compositor/compositor.h"
 
 #include <algorithm>
 #include <deque>
 
 #include "base/bind.h"
@@ skipping 308 matching lines @@
   FOR_EACH_OBSERVER(CompositorAnimationObserver,
                     animation_observer_list_,
                     OnAnimationStep(args.frame_time));
   if (animation_observer_list_.might_have_observers())
     host_->SetNeedsAnimate();
 }
 
 void Compositor::BeginMainFrameNotExpectedSoon() {
 }
 
+static void SendDamagedRectsRecursive(ui::Layer* layer) {
+  layer->SendDamagedRects();
+  for (auto* child : layer->children())

[sky, 2015/04/23 15:53:25]

Why are you moving the recursion here?

[danakj, 2015/04/23 16:02:56]

To make the Layer function a simpler method. The Compositor knows it wants to
send it for all Layers. Layer itself can be more dumb.

+    SendDamagedRectsRecursive(child);
+}
+
 void Compositor::Layout() {
-  if (root_layer_)
-    root_layer_->SendDamagedRects();
+  if (!root_layer())
+    return;
+  SendDamagedRectsRecursive(root_layer());
 }
 
 void Compositor::RequestNewOutputSurface() {
   // TODO(robliao): Remove ScopedTracker below once https://crbug.com/466870
   // is fixed.
   tracked_objects::ScopedTracker tracking_profile(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "466870 Compositor::RequestNewOutputSurface"));
 
   context_factory_->CreateOutputSurface(weak_ptr_factory_.GetWeakPtr());
@@ skipping 75 matching lines @@
                     observer_list_,
                     OnCompositingLockStateChanged(this));
 }
 
 void Compositor::CancelCompositorLock() {
   if (compositor_lock_)
     compositor_lock_->CancelLock();
 }
 
 }  // namespace ui