Replace source pointer in cc::CopyOutputRequest with a base::UnguessableToken

cc/layers/layer.cc

 // Copyright 2010 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/layers/layer.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 334 matching lines @@
 bool Layer::HasAncestor(const Layer* ancestor) const {
   for (const Layer* layer = parent(); layer; layer = layer->parent()) {
     if (layer == ancestor)
       return true;
   }
   return false;
 }
 
 void Layer::RequestCopyOfOutput(std::unique_ptr<CopyOutputRequest> request) {
   DCHECK(IsPropertyChangeAllowed());
-  if (void* source = request->source()) {
+  if (request->has_source()) {
+    const base::UnguessableToken& source = request->source();
     auto it =
         std::find_if(inputs_.copy_requests.begin(), inputs_.copy_requests.end(),
-                     [source](const std::unique_ptr<CopyOutputRequest>& x) {
-                       return x->source() == source;
+                     [&source](const std::unique_ptr<CopyOutputRequest>& x) {
+                       return x->has_source() && x->source() == source;
                      });
     if (it != inputs_.copy_requests.end())
       inputs_.copy_requests.erase(it);
   }
   if (request->IsEmpty())
     return;
   inputs_.copy_requests.push_back(std::move(request));
   SetSubtreePropertyChanged();
   SetNeedsCommit();
 }
@@ skipping 1201 matching lines @@
       ->num_copy_requests_in_subtree;
 }
 
 gfx::Transform Layer::screen_space_transform() const {
   DCHECK_NE(transform_tree_index_, TransformTree::kInvalidNodeId);
   return draw_property_utils::ScreenSpaceTransform(
       this, layer_tree_host_->property_trees()->transform_tree);
 }
 
 }  // namespace cc