Drop frontbuffers with ui-use-gpu-process, synchronized with browser, decoupled from backbuffer dro…

content/common/gpu/gpu_messages.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.
 
 // Multiply-included message file, hence no include guard here, but see below
 // for a much smaller-than-usual include guard section.
 
 #include <vector>
 #include <string>
 
@@ skipping 174 matching lines @@
 
 // Tells the GPU process that the browser process has finished resizing the
 // view.
 IPC_MESSAGE_ROUTED0(AcceleratedSurfaceMsg_ResizeViewACK)
 
 // Tells the GPU process that it's safe to start rendering to the surface.
 IPC_MESSAGE_ROUTED2(AcceleratedSurfaceMsg_NewACK,
                     uint64 /* surface_handle */,
                     TransportDIB::Handle /* shared memory buffer */)
 
+// Tells the GPU process that it's safe to release the surface.
+IPC_MESSAGE_ROUTED2(AcceleratedSurfaceMsg_ReleaseACK,
+                    uint64 /* surface_id */, bool /* success */)
+
 // Tells the GPU process that the browser process handled the swap
 // buffers request.
 IPC_MESSAGE_ROUTED0(AcceleratedSurfaceMsg_BuffersSwappedACK)
 
 // Tells the GPU process that the browser process handled the
 // PostSubBuffer command.
 IPC_MESSAGE_ROUTED0(AcceleratedSurfaceMsg_PostSubBufferACK)
 
 // Tells the GPU process to remove all contexts.
 IPC_MESSAGE_CONTROL0(GpuMsg_Clean)
@@ skipping 306 matching lines @@
 
 // Confirm decoder has been flushed.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_FlushDone)
 
 // Confirm decoder has been reset.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_ResetDone)
 
 // Video decoder has encountered an error.
 IPC_MESSAGE_ROUTED1(AcceleratedVideoDecoderHostMsg_ErrorNotification,
                     uint32) /* Error ID */