[WebView] Add a new flushVisualState API to AwContents.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 0ac71eeed443e1e4c3b300b6601a2f76d394da0d..196da7287e23bdd1d81d23627af6b646348bb0bd 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -920,6 +920,8 @@ bool RenderFrameImpl::OnMessageReceived(const IPC::Message& msg) {
                         OnJavaScriptExecuteRequest)
     IPC_MESSAGE_HANDLER(FrameMsg_JavaScriptExecuteRequestForTests,
                         OnJavaScriptExecuteRequestForTests)
+    IPC_MESSAGE_HANDLER(FrameMsg_FlushVisualStateRequest,
+                        OnFlushVisualStateRequest)
     IPC_MESSAGE_HANDLER(FrameMsg_SetEditableSelectionOffsets,
                         OnSetEditableSelectionOffsets)
     IPC_MESSAGE_HANDLER(FrameMsg_SetupTransitionView, OnSetupTransitionView)
@@ -1386,6 +1388,12 @@ void RenderFrameImpl::HandleJavascriptExecutionResult(
   }
 }
 
+void RenderFrameImpl::OnFlushVisualStateRequest(int id) {
+  GetRenderWidget()->QueueMessage(
+      new FrameHostMsg_FlushVisualStateResponse(routing_id_, id),
+      MESSAGE_DELIVERY_POLICY_WITH_VISUAL_STATE);
+}
+
 void RenderFrameImpl::OnSetEditableSelectionOffsets(int start, int end) {
   base::AutoReset<bool> handling_select_range(&handling_select_range_, true);
   if (!GetRenderWidget()->ShouldHandleImeEvent())