Revert 156318 - I had originally tried to build upon http://codereview.chromium.org/10869066/, but …

ui/compositor/layer.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/layer.h"
 
 #include <algorithm>
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 77 matching lines @@
       delegate_(NULL),
       scale_content_(true),
       device_scale_factor_(1.0f) {
   CreateWebLayer();
 }
 
 Layer::~Layer() {
   // Destroying the animator may cause observers to use the layer (and
   // indirectly the WebLayer). Destroy the animator first so that the WebLayer
   // is still around.
-  if (animator_)
-    animator_->SetDelegate(NULL);
-  animator_ = NULL;
+  animator_.reset();
   if (compositor_)
     compositor_->SetRootLayer(NULL);
   if (parent_)
     parent_->Remove(this);
   if (layer_mask_)
     SetMaskLayer(NULL);
   if (layer_mask_back_link_)
     layer_mask_back_link_->SetMaskLayer(NULL);
   for (size_t i = 0; i < children_.size(); ++i)
     children_[i]->parent_ = NULL;
@@ skipping 58 matching lines @@
   for (const Layer* parent = other; parent; parent = parent->parent()) {
     if (parent == this)
       return true;
   }
   return false;
 }
 
 void Layer::SetAnimator(LayerAnimator* animator) {
   if (animator)
     animator->SetDelegate(this);
-  animator_ = animator;
+  animator_.reset(animator);
 }
 
 LayerAnimator* Layer::GetAnimator() {
   if (!animator_.get())
     SetAnimator(LayerAnimator::CreateDefaultAnimator());
   return animator_.get();
 }
 
 void Layer::SetTransform(const ui::Transform& transform) {
   GetAnimator()->SetTransform(transform);
@@ skipping 585 matching lines @@
     return;
   unsigned int color = 0xFF000000;
   color |= web_layer_is_accelerated_ ? 0x0000FF00 : 0x00FF0000;
   bool opaque = fills_bounds_opaquely_ && (GetCombinedOpacity() == 1.f);
   if (!opaque)
     color |= 0xFF;
   web_layer_->setDebugBorderColor(color);
 }
 
 }  // namespace ui