Revert of Keep a copy of page id in RenderViewHost.

content/browser/renderer_host/render_view_host_impl.h

Index: content/browser/renderer_host/render_view_host_impl.h
diff --git a/content/browser/renderer_host/render_view_host_impl.h b/content/browser/renderer_host/render_view_host_impl.h
index b099a7b280f63bef518c334f79777250201be3dc..e2a97648b6317adaadf1d23a78f26b0530f14a46 100644
--- a/content/browser/renderer_host/render_view_host_impl.h
+++ b/content/browser/renderer_host/render_view_host_impl.h
@@ -547,11 +547,6 @@
   // TODO(nasko): Move to RenderFrameHost, as this is per-frame state.
   scoped_ptr<FrameMsg_Navigate_Params> suspended_nav_params_;
 
-  // 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_;
-
   // The current state of this RVH.
   // TODO(nasko): Move to RenderFrameHost, as this is per-frame state.
   RenderViewHostImplState rvh_state_;