sync compositor: Async scroll offset IPC

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 8294fcd1eec8ff923c67b20c7fa9debf5ba59684..0f7bf23cd5d2b5f9a3689a2d4b2355313c9e36cc 100644
--- a/content/common/android/sync_compositor_messages.h
+++ b/content/common/android/sync_compositor_messages.h
@@ -26,8 +26,6 @@ struct SyncCompositorCommonBrowserParams {
   SyncCompositorCommonBrowserParams();
   ~SyncCompositorCommonBrowserParams();
 
-  gfx::ScrollOffset root_scroll_offset;
-  bool update_root_scroll_offset;
   bool begin_frame_source_paused;
 };
 
@@ -94,8 +92,6 @@ struct SyncCompositorCommonRendererParams {
 #define IPC_MESSAGE_START SyncCompositorMsgStart
 
 IPC_STRUCT_TRAITS_BEGIN(content::SyncCompositorCommonBrowserParams)
-  IPC_STRUCT_TRAITS_MEMBER(root_scroll_offset)
-  IPC_STRUCT_TRAITS_MEMBER(update_root_scroll_offset)
   IPC_STRUCT_TRAITS_MEMBER(begin_frame_source_paused)
 IPC_STRUCT_TRAITS_END()
 
@@ -190,6 +186,8 @@ IPC_MESSAGE_ROUTED2(SyncCompositorMsg_ReclaimResources,
                     uint32_t /* output_surface_id */,
                     cc::CompositorFrameAck);
 
+IPC_MESSAGE_ROUTED1(SyncCompositorMsg_SetScroll, gfx::ScrollOffset);
+
 // -----------------------------------------------------------------------------
 // Messages sent from the renderer to the browser.