Fix the browser not being notified when a webview embedder handles a navigation.

content/common/frame_messages.h

 // Copyright 2013 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.
 
 // IPC messages for interacting with frames.
 // Multiply-included message file, hence no include guard.
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 1593 matching lines @@
 IPC_MESSAGE_ROUTED3(FrameHostMsg_FindMatchRects_Reply,
                     int /* version */,
                     std::vector<gfx::RectF> /* rects */,
                     gfx::RectF /* active_rect */)
 
 // Response to FrameMsg_GetNearestFindResult. |distance| is the distance to the
 // nearest find result in the sending frame.
 IPC_MESSAGE_ROUTED2(FrameHostMsg_GetNearestFindResult_Reply,
                     int /* nfr_request_id */,
                     float /* distance */)
+
+IPC_MESSAGE_ROUTED0(FrameHostMsg_NavigationHandledByEmbedder)
 #endif
 
 // Adding a new message? Stick to the sort order above: first platform
 // independent FrameMsg, then ifdefs for platform specific FrameMsg, then
 // platform independent FrameHostMsg, then ifdefs for platform specific
 // FrameHostMsg.