Ensure that the browser’s copy of page id is in sync with the renderer’s.

content/browser/frame_host/render_frame_host_impl.cc

 // 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.
 
 #include "content/browser/frame_host/render_frame_host_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/containers/hash_tables.h"
 #include "base/lazy_instance.h"
@@ skipping 1033 matching lines @@
 void RenderFrameHostImpl::OnDidAssignPageId(int32 page_id) {
   // Update the RVH's current page ID so that future IPCs from the renderer
   // correspond to the new page.
   render_view_host_->page_id_ = page_id;
 }
 
 void RenderFrameHostImpl::OnUpdateTitle(
     int32 page_id,
     const base::string16& title,
     blink::WebTextDirection title_direction) {
+  CHECK_EQ(render_view_host_->page_id_, page_id);
   // This message is only sent for top-level frames. TODO(avi): when frame tree
   // mirroring works correctly, add a check here to enforce it.
   if (title.length() > kMaxTitleChars) {
     NOTREACHED() << "Renderer sent too many characters in title.";
     return;
   }
 
   delegate_->UpdateTitle(this, page_id, title,
                          WebTextDirectionToChromeTextDirection(
                              title_direction));
@@ skipping 498 matching lines @@
   // Clear any state if a pending navigation is canceled or preempted.
   if (suspended_nav_params_)
     suspended_nav_params_.reset();
 
   TRACE_EVENT_ASYNC_END0("navigation",
                          "RenderFrameHostImpl navigation suspended", this);
   navigations_suspended_ = false;
 }
 
 }  // namespace content