cc: Resize picture layer tiling set during commit

cc/picture_layer_tiling_set.cc

 // Copyright 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 "cc/picture_layer_tiling_set.h"
 
 namespace cc {
 
 PictureLayerTilingSet::PictureLayerTilingSet(
     PictureLayerTilingClient * client)
     : client_(client) {
 }
 
 PictureLayerTilingSet::~PictureLayerTilingSet() {
 }
 
 void PictureLayerTilingSet::CloneFrom(const PictureLayerTilingSet& other) {
   layer_bounds_ = other.layer_bounds_;
   tilings_.clear();
   tilings_.reserve(other.tilings_.size());
   for (size_t i = 0; i < other.tilings_.size(); ++i) {
     tilings_.append(other.tilings_[i]->Clone());
   }
 }
 
 void PictureLayerTilingSet::SetLayerBounds(gfx::Size layer_bounds) {
+  if (layer_bounds_ == layer_bounds)
+    return;
   layer_bounds_ = layer_bounds;
   for (size_t i = 0; i < tilings_.size(); ++i)
     tilings_[i]->SetLayerBounds(layer_bounds);
 }
 
 gfx::Size PictureLayerTilingSet::LayerBounds() const {
   return layer_bounds_;
 }
 
 void PictureLayerTilingSet::Invalidate(const Region& invalidation) {
@@ skipping 133 matching lines @@
     const gfx::Transform& current_screen_transform,
     double time_delta) {
   for (size_t i = 0; i < tilings_.size(); ++i) {
     tilings_[i]->UpdateTilePriorities(
         device_viewport, layer_content_scale_x, layer_content_scale_y,
         last_screen_transform, current_screen_transform, time_delta);
   }
 }
 
 }  // namespace cc