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

gpu/command_buffer/service/gles2_cmd_decoder.h

Index: gpu/command_buffer/service/gles2_cmd_decoder.h
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.h b/gpu/command_buffer/service/gles2_cmd_decoder.h
index b689a0ca8da5464e9bf6fc8349c72d11d34fbe53..1dff9fccaec502c32ecd8b25c70c8458a69d5a7a 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.h
@@ -33,6 +33,7 @@ class Size;
 namespace gpu {
 
 struct Mailbox;
+struct SyncToken;
 
 namespace gles2 {
 
@@ -158,7 +159,13 @@ class GPU_EXPORT GLES2Decoder : public base::SupportsWeakPtr<GLES2Decoder>,
   // 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;
@@ -200,6 +207,8 @@ class GPU_EXPORT GLES2Decoder : public base::SupportsWeakPtr<GLES2Decoder>,
   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;