Avoid stale navigation requests without excessive page id knowledge in the renderer process.

content/browser/web_contents/web_contents_impl.h

Index: content/browser/web_contents/web_contents_impl.h
diff --git a/content/browser/web_contents/web_contents_impl.h b/content/browser/web_contents/web_contents_impl.h
index a747fe8c9f3d4a9557951a8e017ea5c2f47ba498..339865a636f2d335170927bbd464ecc99f48d1ca 100644
--- a/content/browser/web_contents/web_contents_impl.h
+++ b/content/browser/web_contents/web_contents_impl.h
@@ -611,13 +611,10 @@ class CONTENT_EXPORT WebContentsImpl
   bool NavigateToPendingEntry(
       NavigationController::ReloadType reload_type) override;
 
-  // Sets the history for this WebContentsImpl to |history_length| entries, and
-  // moves the current page_id to the last entry in the list if it's valid.
-  // This is mainly used when a prerendered page is swapped into the current
-  // tab. The method is virtual for testing.
-  void SetHistoryLengthAndPrune(const SiteInstance* site_instance,
-                                int merge_history_length,
-                                int32 minimum_page_id) override;
+  // Sets the history for this WebContentsImpl to |history_length| entries, with
+  // an offset of |history_offset|.
+  void SetHistoryOffsetAndLength(int history_offset,
+                                 int history_length) override;
 
   // Called by InterstitialPageImpl when it creates a RenderFrameHost.
   void RenderFrameForInterstitialPageCreated(
@@ -886,6 +883,12 @@ class CONTENT_EXPORT WebContentsImpl
 
   // Misc non-view stuff -------------------------------------------------------
 
+  // Sets the history for a specified RenderViewHost to |history_length|
+  // entries, with an offset of |history_offset|.
+  void SetHistoryOffsetAndLengthForView(RenderViewHost* render_view_host,
+                                        int history_offset,
+                                        int history_length);
+
   // Helper functions for sending notifications.
   void NotifyViewSwapped(RenderViewHost* old_host, RenderViewHost* new_host);
   void NotifyFrameSwapped(RenderFrameHost* old_host, RenderFrameHost* new_host);