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

content/common/gpu/gpu_messages.h

Index: content/common/gpu/gpu_messages.h
diff --git a/content/common/gpu/gpu_messages.h b/content/common/gpu/gpu_messages.h
index 945928b963995acf6c6290df0bd94650d8622502..8c18a4642247eea4d03d3e72eac4919d9f93886e 100644
--- a/content/common/gpu/gpu_messages.h
+++ b/content/common/gpu/gpu_messages.h
@@ -84,6 +84,14 @@ IPC_STRUCT_BEGIN(GpuHostMsg_AcceleratedSurfaceRelease_Params)
 #endif
 IPC_STRUCT_END()
 
+IPC_STRUCT_BEGIN(GpuHostMsg_AcceleratedSurfaceRequestReleaseFront_Params)
+  IPC_STRUCT_MEMBER(int32, surface_id)
+  IPC_STRUCT_MEMBER(uint64, identifier)
+  IPC_STRUCT_MEMBER(int32, route_id)
+  IPC_STRUCT_MEMBER(int, request_id)
+  IPC_STRUCT_MEMBER(int, retry_count)
+IPC_STRUCT_END()
+
 IPC_STRUCT_BEGIN(GPUCommandBufferConsoleMessage)
   IPC_STRUCT_MEMBER(int32, id)
   IPC_STRUCT_MEMBER(std::string, message)
@@ -200,6 +208,16 @@ IPC_MESSAGE_ROUTED2(AcceleratedSurfaceMsg_NewACK,
                     uint64 /* surface_handle */,
                     TransportDIB::Handle /* shared memory buffer */)
 
+// Tells the GPU process that it can now safely release the front surface.
+IPC_MESSAGE_ROUTED3(AcceleratedSurfaceMsg_RequestReleaseFrontACK,
+                    int /* request_id */,
+                    int /* retry_count */,
+                    bool /* was_released */)
+
+// Tells the GPU process if it's worth suggesting release of the front surface.
+IPC_MESSAGE_ROUTED1(AcceleratedSurfaceMsg_SetFrontSurfaceIsProtected,
+                    bool /* is_protected */)
+
 // Tells the GPU process that the browser process handled the swap
 // buffers request.
 IPC_MESSAGE_ROUTED0(AcceleratedSurfaceMsg_BuffersSwappedACK)
@@ -295,6 +313,10 @@ IPC_MESSAGE_CONTROL1(GpuHostMsg_AcceleratedSurfaceRelease,
 IPC_MESSAGE_CONTROL1(GpuHostMsg_AcceleratedSurfaceSuspend,
                      int32 /* surface_id */)
 
+// Tells the browser to release its handle to the given frontbuffer surface.
+IPC_MESSAGE_CONTROL1(GpuHostMsg_AcceleratedSurfaceRequestReleaseFront,
+                     GpuHostMsg_AcceleratedSurfaceRequestReleaseFront_Params)
+
 //------------------------------------------------------------------------------
 // GPU Channel Messages
 // These are messages from a renderer process to the GPU process.