Remove the extra copy of page id.

content/browser/renderer_host/render_view_host_impl.h

 // Copyright (c) 2012 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_VIEW_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_VIEW_HOST_IMPL_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 392 matching lines @@
   scoped_refptr<SiteInstanceImpl> instance_;
 
   // true if we are currently waiting for a response for drag context
   // information.
   bool waiting_for_drag_context_response_;
 
   // A bitwise OR of bindings types that have been enabled for this RenderView.
   // See BindingsPolicy for details.
   int enabled_bindings_;
 
-  // The most recent page ID we've heard from the renderer process.  This is
-  // used as context when other session history related IPCs arrive.
-  // TODO(creis): Allocate this in WebContents/NavigationController instead.
-  int32 page_id_;

[Charlie Reis, 2015/05/13 17:17:51]

To get UpdateTitle and UpdateState to work when cross-process navigations may
have recently committed, I think we need each RVH (or RFH?) to know which
NavigationEntry it's on.

We don't need page ID for this (since it's going away), but we need something. 
Unique ID would probably work.

-
   // Tracks whether this RenderViewHost is in an active state.  False if the
   // main frame is pending swap out, pending deletion, or swapped out, because
   // it is not visible to the user in any of these cases.
   bool is_active_;
 
   // Tracks whether the main frame RenderFrameHost is swapped out.  Unlike
   // is_active_, this is false when the frame is pending swap out or deletion.
   // TODO(creis): Remove this when we no longer use swappedout://.
   // See http://crbug.com/357747.
   bool is_swapped_out_;
@@ skipping 30 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(RenderViewHostImpl);
 };
 
 #if defined(COMPILER_MSVC)
 #pragma warning(pop)
 #endif
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_VIEW_HOST_IMPL_H_