Require ACK for editor-related changes not originating from browser.

content/common/view_messages.h

Index: content/common/view_messages.h
diff --git a/content/common/view_messages.h b/content/common/view_messages.h
index b4074bf11881ccb4658fd910224728594eb6fd3e..a5ead5bb4d3bec2d6d1986a6c5dfc2ba8e058ae4 100644
--- a/content/common/view_messages.h
+++ b/content/common/view_messages.h
@@ -1316,6 +1316,10 @@ IPC_MESSAGE_ROUTED1(ViewMsg_SelectPopupMenuItem,
                     int /* selected index, -1 means no selection */)
 #endif
 
+// Sent by the browser when an IME update that requires acknowledgement has been
+// processed on the browser side.
+IPC_MESSAGE_ROUTED0(ViewMsg_AcknowledgeImeEvent)
+
 // Sent by the browser as a reply to ViewHostMsg_SwapCompositorFrame.
 IPC_MESSAGE_ROUTED1(ViewMsg_SwapCompositorFrameAck,
                     cc::CompositorFrameAck /* ack */)