InProcessGL: Share MailboxManager per service

gpu/command_buffer/service/in_process_command_buffer.h

Index: gpu/command_buffer/service/in_process_command_buffer.h
diff --git a/gpu/command_buffer/service/in_process_command_buffer.h b/gpu/command_buffer/service/in_process_command_buffer.h
index 531d0ef6882c018cebb30e0afe7e743dc98d1dca..91b148ed2f768de3296cfc0908d4130d9a59d0c5 100644
--- a/gpu/command_buffer/service/in_process_command_buffer.h
+++ b/gpu/command_buffer/service/in_process_command_buffer.h
@@ -48,6 +48,7 @@ namespace gpu {
 
 namespace gles2 {
 class GLES2Decoder;
+class MailboxManager;
 class ShaderTranslatorCache;
 }
 
@@ -153,6 +154,10 @@ class GPU_EXPORT InProcessCommandBuffer : public CommandBuffer,
     virtual bool UseVirtualizedGLContexts() = 0;
     virtual scoped_refptr<gles2::ShaderTranslatorCache>
         shader_translator_cache() = 0;
+    scoped_refptr<gles2::MailboxManager> mailbox_manager();
+
+   protected:
+    scoped_refptr<gles2::MailboxManager> mailbox_manager_;
   };
 
 #if defined(OS_ANDROID)