Switching to base::Optional<CompositorFrame> in Android's synchronous compositor IPC messages

content/common/android/sync_compositor_messages.h

Index: content/common/android/sync_compositor_messages.h
diff --git a/content/common/android/sync_compositor_messages.h b/content/common/android/sync_compositor_messages.h
index e7e41d6e5d0d5d744a63be8402a8644cdfe1fd79..78311670434a3f76ff39d4c4e551a500170fbe3e 100644
--- a/content/common/android/sync_compositor_messages.h
+++ b/content/common/android/sync_compositor_messages.h
@@ -127,11 +127,12 @@ IPC_MESSAGE_ROUTED1(SyncCompositorMsg_ComputeScroll,
 IPC_MESSAGE_ROUTED1(SyncCompositorMsg_DemandDrawHwAsync,
                     content::SyncCompositorDemandDrawHwParams)
 
-IPC_SYNC_MESSAGE_ROUTED1_3(SyncCompositorMsg_DemandDrawHw,
+IPC_SYNC_MESSAGE_ROUTED1_4(SyncCompositorMsg_DemandDrawHw,
                            content::SyncCompositorDemandDrawHwParams,
                            content::SyncCompositorCommonRendererParams,
                            uint32_t /* compositor_frame_sink_id */,
-                           cc::CompositorFrame)
+                           cc::CompositorFrame,

[boliu, 2016/10/27 18:11:46]

might be easier to replace this with base::Optional<cc::CompositorFrame> ?

Looks like there's a ParamTraits for base::Optional already, so it should just
work?

+                           bool /* has_swapped */)
 
 IPC_SYNC_MESSAGE_ROUTED1_2(SyncCompositorMsg_SetSharedMemory,
                            content::SyncCompositorSetSharedMemoryParams,
@@ -168,6 +169,7 @@ IPC_MESSAGE_ROUTED0(SyncCompositorHostMsg_CompositorFrameSinkCreated);
 IPC_MESSAGE_ROUTED1(SyncCompositorHostMsg_UpdateState,
                     content::SyncCompositorCommonRendererParams)
 
-IPC_MESSAGE_ROUTED2(SyncCompositorHostMsg_ReturnFrame,
+IPC_MESSAGE_ROUTED3(SyncCompositorHostMsg_ReturnFrame,
                     uint32_t /* compositor_frame_sink_id */,
-                    cc::CompositorFrame);
+                    cc::CompositorFrame,
+                    bool /* has_swapped */);