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

gpu/command_buffer/service/gles2_cmd_decoder.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.
 
 // This file contains the GLES2Decoder class.
 
 #ifndef GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_
 #define GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_
 
 #include <stdint.h>
@@ skipping 15 matching lines @@
 
 namespace gfx {
 class GLContext;
 class GLSurface;
 class Size;
 }
 
 namespace gpu {
 
 struct Mailbox;
+struct SyncToken;
 
 namespace gles2 {
 
 class ContextGroup;
 class ErrorState;
 class GLES2Util;
 class ImageManager;
 class Logger;
 class QueryManager;
 class Texture;
@@ skipping 105 matching lines @@
                           const gfx::Size& offscreen_size,
                           const DisallowedFeatures& disallowed_features,
                           const std::vector<int32_t>& attribs) = 0;
 
   // Destroys the graphics context.
   virtual void Destroy(bool have_context) = 0;
 
   // Set the surface associated with the default FBO.
   virtual void SetSurface(const scoped_refptr<gfx::GLSurface>& surface) = 0;
 
-  virtual void ProduceFrontBuffer(const Mailbox& mailbox) = 0;
+  // Releases the surface associated with the GL context.
+  // The decoder should not be used until a new surface is set.
+  virtual void ReleaseSurface() = 0;

[piman, 2016/04/26 01:54:01]

Is this a leftover from a merge conflict? (This was added in a patch that landed
and was reverted a couple of times - https://codereview.chromium.org/1714883002/
- but it doesn't seem related to your change)

[erikchen, 2016/04/27 16:31:23]

Whoops! Removed

+
+  virtual void TakeFrontBuffer(const Mailbox& mailbox) = 0;
+  virtual void ReturnFrontBuffer(const Mailbox& mailbox,
+                                 bool is_lost) = 0;
 
   // Resize an offscreen frame buffer.
   virtual bool ResizeOffscreenFrameBuffer(const gfx::Size& size) = 0;
 
   // Make this decoder's GL context current.
   virtual bool MakeCurrent() = 0;
 
   // Gets the GLES2 Util which holds info.
   virtual GLES2Util* GetGLES2Util() = 0;
 
@@ skipping 21 matching lines @@
   virtual void RestoreTextureState(unsigned service_id) const = 0;
   virtual void RestoreTextureUnitBindings(unsigned unit) const = 0;
   virtual void RestoreAllExternalTextureBindingsIfNeeded() = 0;
 
   virtual void ClearAllAttributes() const = 0;
   virtual void RestoreAllAttributes() const = 0;
 
   virtual void SetIgnoreCachedStateForTest(bool ignore) = 0;
   virtual void SetForceShaderNameHashingForTest(bool force) = 0;
   virtual uint32_t GetAndClearBackbufferClearBitsForTest();
+  virtual size_t GetSavedBackTextureCountForTest() = 0;
+  virtual size_t GetCreatedBackTextureCountForTest() = 0;
 
   // Gets the QueryManager for this context.
   virtual QueryManager* GetQueryManager() = 0;
 
   // Gets the VertexArrayManager for this context.
   virtual VertexArrayManager* GetVertexArrayManager() = 0;
 
   // Gets the ImageManager for this context.
   virtual ImageManager* GetImageManager() = 0;
 
@@ skipping 84 matching lines @@
   bool log_commands_;
   bool unsafe_es3_apis_enabled_;
   bool force_shader_name_hashing_for_test_;
   DISALLOW_COPY_AND_ASSIGN(GLES2Decoder);
 };
 
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_