cc: Prevent integer overflow with software TextureMailbox.

cc/resources/texture_mailbox.h

 // 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.
 
 #ifndef CC_RESOURCES_TEXTURE_MAILBOX_H_
 #define CC_RESOURCES_TEXTURE_MAILBOX_H_
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/memory/shared_memory.h"
+#include "base/numerics/safe_math.h"
 #include "cc/base/cc_export.h"
 #include "gpu/command_buffer/common/mailbox_holder.h"
 #include "ui/gfx/size.h"
 
 namespace cc {
 
 // TODO(skaslev, danakj) Rename this class more apropriately since now it
 // can hold a shared memory resource as well as a texture mailbox.
 class CC_EXPORT TextureMailbox {
  public:
@@ skipping 16 matching lines @@
   uint32 sync_point() const { return mailbox_holder_.sync_point; }
   void set_sync_point(int32 sync_point) {
     mailbox_holder_.sync_point = sync_point;
   }
 
   bool allow_overlay() const { return allow_overlay_; }
   void set_allow_overlay(bool allow_overlay) { allow_overlay_ = allow_overlay; }
 
   base::SharedMemory* shared_memory() const { return shared_memory_; }
   gfx::Size shared_memory_size() const { return shared_memory_size_; }
-  size_t shared_memory_size_in_bytes() const;
+
+  size_t SharedMemorySizeInBytes() const;
+  base::CheckedNumeric<size_t> CheckedSharedMemorySizeInBytes() const;
 
  private:
   gpu::MailboxHolder mailbox_holder_;
   base::SharedMemory* shared_memory_;
   gfx::Size shared_memory_size_;
   bool allow_overlay_;
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_TEXTURE_MAILBOX_H_