sync compositor: Async scroll offset IPC

content/renderer/android/synchronous_compositor_proxy.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/android/synchronous_compositor_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/memory/shared_memory.h"
 #include "content/common/android/sync_compositor_messages.h"
@@ skipping 156 matching lines @@
     IPC_MESSAGE_HANDLER(SyncCompositorMsg_BeginFrame, BeginFrame)
     IPC_MESSAGE_HANDLER(SyncCompositorMsg_ComputeScroll, OnComputeScroll)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(SyncCompositorMsg_DemandDrawHw,
                                     DemandDrawHw)
     IPC_MESSAGE_HANDLER(SyncCompositorMsg_SetSharedMemory, SetSharedMemory)
     IPC_MESSAGE_HANDLER(SyncCompositorMsg_ZeroSharedMemory, ZeroSharedMemory)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(SyncCompositorMsg_DemandDrawSw,
                                     DemandDrawSw)
     IPC_MESSAGE_HANDLER(SyncCompositorMsg_UpdateState, ProcessCommonParams)
     IPC_MESSAGE_HANDLER(SyncCompositorMsg_ZoomBy, SynchronouslyZoomBy)
+    IPC_MESSAGE_HANDLER(SyncCompositorMsg_SetScroll, SetScroll)
   IPC_END_MESSAGE_MAP()
 }
 
 bool SynchronousCompositorProxy::Send(IPC::Message* message) {
   return sender_->Send(message);
 }
 
 void SynchronousCompositorProxy::HandleInputEvent(
     const SyncCompositorCommonBrowserParams& common_params,
     const blink::WebInputEvent* event,
@@ skipping 205 matching lines @@
     float zoom_delta,
     const gfx::Point& anchor,
     SyncCompositorCommonRendererParams* common_renderer_params) {
   DCHECK(!inside_receive_);
   base::AutoReset<bool> scoped_inside_receive(&inside_receive_, true);
   ProcessCommonParams(common_params);
   input_handler_proxy_->SynchronouslyZoomBy(zoom_delta, anchor);
   PopulateCommonParams(common_renderer_params);
 }
 
+void SynchronousCompositorProxy::SetScroll(
+    const gfx::ScrollOffset& new_total_scroll_offset) {
+  if (total_scroll_offset_ == new_total_scroll_offset)
+    return;
+  total_scroll_offset_ = new_total_scroll_offset;
+  input_handler_proxy_->SynchronouslySetRootScrollOffset(total_scroll_offset_);
+}
+
 void SynchronousCompositorProxy::DidOverscroll(
     const DidOverscrollParams& did_overscroll_params) {
   SyncCompositorCommonRendererParams params;
   PopulateCommonParams(&params);
   Send(new SyncCompositorHostMsg_OverScroll(routing_id_, params,
                                             did_overscroll_params));
 }
 
 void SynchronousCompositorProxy::ProcessCommonParams(
     const SyncCompositorCommonBrowserParams& common_params) {
-  if (common_params.update_root_scroll_offset &&
-      total_scroll_offset_ != common_params.root_scroll_offset) {
-    total_scroll_offset_ = common_params.root_scroll_offset;
-    input_handler_proxy_->SynchronouslySetRootScrollOffset(
-        total_scroll_offset_);
-  }
   begin_frame_source_->SetBeginFrameSourcePaused(
       common_params.begin_frame_source_paused);
 }
 
 }  // namespace content