Pepper takes ownership of a mailbox before passing it to the texture layer.

gpu/ipc/service/gpu_command_buffer_stub.h

 // 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.
 
 #ifndef GPU_IPC_SERVICE_GPU_COMMAND_BUFFER_STUB_H_
 #define GPU_IPC_SERVICE_GPU_COMMAND_BUFFER_STUB_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 146 matching lines @@
 
   // Cleans up and sends reply if OnInitialize failed.
   void OnInitializeFailed(IPC::Message* reply_message);
 
   scoped_refptr<gfx::GLSurface> CreateSurface();
 
   // Message handlers:
   void OnInitialize(base::SharedMemoryHandle shared_state_shm,
                     IPC::Message* reply_message);
   void OnSetGetBuffer(int32_t shm_id, IPC::Message* reply_message);
-  void OnProduceFrontBuffer(const Mailbox& mailbox);
+  void OnTakeFrontBuffer(const Mailbox& mailbox);
+  void OnReturnFrontBuffer(const Mailbox& mailbox,
+                           const SyncToken& sync_token,
+                           bool is_lost);
   void OnGetState(IPC::Message* reply_message);
   void OnWaitForTokenInRange(int32_t start,
                              int32_t end,
                              IPC::Message* reply_message);
   void OnWaitForGetOffsetInRange(int32_t start,
                                  int32_t end,
                                  IPC::Message* reply_message);
   void OnAsyncFlush(int32_t put_offset,
                     uint32_t flush_count,
                     const std::vector<ui::LatencyInfo>& latency_info);
@@ skipping 99 matching lines @@
 
   std::unique_ptr<WaitForCommandState> wait_for_token_;
   std::unique_ptr<WaitForCommandState> wait_for_get_offset_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuCommandBufferStub);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_IPC_SERVICE_GPU_COMMAND_BUFFER_STUB_H_