Add comments for struct members that were changed from size_t to uin32_t or uint64_t for IPC safety.

content/common/gpu/gpu_memory_manager.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 "content/common/gpu/gpu_memory_manager.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 100 matching lines @@
   video_memory_usage_stats->bytes_allocated_historical_max =
       bytes_allocated_historical_max_;
 }
 
 void GpuMemoryManager::SendUmaStatsToBrowser() {
   if (!channel_manager_)
     return;
   GPUMemoryUmaStats params;
   params.bytes_allocated_current = GetCurrentUsage();
   params.bytes_allocated_max = bytes_allocated_historical_max_;
-  params.context_group_count = tracking_groups_.size();
+  params.context_group_count = static_cast<uint32_t>(tracking_groups_.size());
   channel_manager_->Send(new GpuHostMsg_GpuMemoryUmaStats(params));
 }
 }  // namespace content