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 049785f3fa3ed62fcff0f141db060393751ab73e..77a8831a687bd2f0f85ee4ac834a664aa0dac8e3 100644
--- a/content/common/gpu/gpu_messages.h
+++ b/content/common/gpu/gpu_messages.h
@@ -58,6 +58,8 @@ IPC_STRUCT_BEGIN(GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params)
 #elif defined(OS_MACOSX)
   IPC_STRUCT_MEMBER(gfx::PluginWindowHandle, window)
 #endif
+  IPC_STRUCT_MEMBER(uint32, protection_state_id)
+  IPC_STRUCT_MEMBER(bool, require_ack)
 IPC_STRUCT_END()
 #undef IPC_MESSAGE_EXPORT
 #define IPC_MESSAGE_EXPORT
@@ -73,6 +75,7 @@ IPC_STRUCT_BEGIN(GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params)
 #if defined(OS_MACOSX)
   IPC_STRUCT_MEMBER(gfx::PluginWindowHandle, window)
 #endif
+  IPC_STRUCT_MEMBER(uint32, protection_state_id)
 IPC_STRUCT_END()
 
 IPC_STRUCT_BEGIN(GpuHostMsg_AcceleratedSurfaceRelease_Params)
@@ -200,6 +203,11 @@ IPC_MESSAGE_ROUTED2(AcceleratedSurfaceMsg_NewACK,
                     uint64 /* surface_handle */,
                     TransportDIB::Handle /* shared memory buffer */)
 
+// Tells the GPU process if it's worth suggesting release of the front surface.
+IPC_MESSAGE_ROUTED2(AcceleratedSurfaceMsg_SetFrontSurfaceIsProtected,
+                    bool /* is_protected */,
+                    uint32 /* protection_state_id */)
+
 // Tells the GPU process that the browser process handled the swap
 // buffers request.
 IPC_MESSAGE_ROUTED0(AcceleratedSurfaceMsg_BuffersSwappedACK)