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 55a880c93f2326b08d2251a809ef8bd158345775..2415fa8661e3c31b2b7345b16c2643727e948519 100644
--- a/content/common/gpu/gpu_messages.h
+++ b/content/common/gpu/gpu_messages.h
@@ -62,6 +62,8 @@ 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, skip_ack)
 IPC_STRUCT_END()
 #undef IPC_MESSAGE_EXPORT
 #define IPC_MESSAGE_EXPORT
@@ -77,6 +79,7 @@ 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)
@@ -222,6 +225,11 @@ IPC_MESSAGE_CONTROL0(GpuMsg_CollectGraphicsInfo)
 // view.
 IPC_MESSAGE_ROUTED0(AcceleratedSurfaceMsg_ResizeViewACK)
 
+// 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 has handled the swap
 // buffers or post sub-buffer request. A non-zero sync point means
 // that we should wait for the sync point.