DRAFT CL: Check that we already know the renderer's page ID (outside commit).

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 6460cd3ecc6b4b2f89a3efb8277e4bc0fc9c8de8..a87e477a63a04bc4464e53cd4b98ee3dcb64c331 100644
--- a/content/browser/renderer_host/render_view_host_impl.h
+++ b/content/browser/renderer_host/render_view_host_impl.h
@@ -584,6 +584,11 @@ class CONTENT_EXPORT RenderViewHostImpl
   // 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 the browser process instead.
+  int32 page_id_;
+
   // The current state of this RVH.
   // TODO(nasko): Move to RenderFrameHost, as this is per-frame state.
   RenderViewHostImplState rvh_state_;