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

cc/output/copy_output_request.cc

 // Copyright 2013 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/output/copy_output_request.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/logging.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 10 matching lines @@
   std::unique_ptr<CopyOutputRequest> relay = CreateRequest(result_callback);
   relay->force_bitmap_result_ = original_request.force_bitmap_result_;
   relay->has_area_ = original_request.has_area_;
   relay->area_ = original_request.area_;
   relay->has_texture_mailbox_ = original_request.has_texture_mailbox_;
   relay->texture_mailbox_ = original_request.texture_mailbox_;
   return relay;
 }
 
 CopyOutputRequest::CopyOutputRequest()
-    : source_(nullptr),
-      force_bitmap_result_(false),
+    : force_bitmap_result_(false),
       has_area_(false),
       has_texture_mailbox_(false) {}
 
 CopyOutputRequest::CopyOutputRequest(
     bool force_bitmap_result,
     const CopyOutputRequestCallback& result_callback)
-    : source_(nullptr),
-      force_bitmap_result_(force_bitmap_result),
+    : force_bitmap_result_(force_bitmap_result),
       has_area_(false),
       has_texture_mailbox_(false),
       result_callback_(result_callback) {
   DCHECK(!result_callback_.is_null());
   TRACE_EVENT_ASYNC_BEGIN0("cc", "CopyOutputRequest", this);
 }
 
 CopyOutputRequest::~CopyOutputRequest() {
   if (!result_callback_.is_null())
     SendResult(CopyOutputResult::CreateEmptyResult());
@@ skipping 24 matching lines @@
 
 void CopyOutputRequest::SetTextureMailbox(
     const TextureMailbox& texture_mailbox) {
   DCHECK(!force_bitmap_result_);
   DCHECK(texture_mailbox.IsTexture());
   has_texture_mailbox_ = true;
   texture_mailbox_ = texture_mailbox;
 }
 
 }  // namespace cc