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

gpu/ipc/client/command_buffer_proxy_impl.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_CLIENT_COMMAND_BUFFER_PROXY_IMPL_H_
 #define GPU_IPC_CLIENT_COMMAND_BUFFER_PROXY_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 96 matching lines @@
   gpu::CommandBufferId GetCommandBufferID() const override;
   int32_t GetExtraCommandBufferData() const override;
   uint64_t GenerateFenceSyncRelease() override;
   bool IsFenceSyncRelease(uint64_t release) override;
   bool IsFenceSyncFlushed(uint64_t release) override;
   bool IsFenceSyncFlushReceived(uint64_t release) override;
   void SignalSyncToken(const gpu::SyncToken& sync_token,
                        const base::Closure& callback) override;
   bool CanWaitUnverifiedSyncToken(const gpu::SyncToken* sync_token) override;
 
-  bool ProduceFrontBuffer(const gpu::Mailbox& mailbox);
+  void TakeFrontBuffer(const gpu::Mailbox& mailbox);
+  void ReturnFrontBuffer(const gpu::Mailbox& mailbox,
+                         const gpu::SyncToken& sync_token,
+                         bool is_lost);
 
   void AddDeletionObserver(DeletionObserver* observer);
   void RemoveDeletionObserver(DeletionObserver* observer);
 
   bool EnsureBackbuffer();
 
   void SetOnConsoleMessageCallback(const GpuConsoleMessageCallback& callback);
 
   void SetLatencyInfo(const std::vector<ui::LatencyInfo>& latency_info);
   using SwapBuffersCompletionCallback =
@@ skipping 119 matching lines @@
 
   base::WeakPtr<CommandBufferProxyImpl> weak_this_;
   scoped_refptr<base::SequencedTaskRunner> callback_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(CommandBufferProxyImpl);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_IPC_CLIENT_COMMAND_BUFFER_PROXY_IMPL_H_