Fix incorrect creation of duplicate navigation entries for repeated page load failures.

content/browser/frame_host/navigation_controller_impl.h

Index: content/browser/frame_host/navigation_controller_impl.h
diff --git a/content/browser/frame_host/navigation_controller_impl.h b/content/browser/frame_host/navigation_controller_impl.h
index c7df11d36fa8b403ade443fcfea012aeda3a204b..aab0f16f25fa142523cef758c6f287f73cc94ef7 100644
--- a/content/browser/frame_host/navigation_controller_impl.h
+++ b/content/browser/frame_host/navigation_controller_impl.h
@@ -199,8 +199,9 @@ class CONTENT_EXPORT NavigationControllerImpl
   // that.
   void SetScreenshotManager(NavigationEntryScreenshotManager* manager);
 
-  // Discards only the pending entry.
-  void DiscardPendingEntry();
+  // Discards only the pending entry. |was_failure| should be set if the pending
+  // entry is being discarded because it failed to load.
+  void DiscardPendingEntry(bool was_failure);
 
  private:
   friend class RestoreHelper;
@@ -345,11 +346,15 @@ class CONTENT_EXPORT NavigationControllerImpl
   // the memory management.
   NavigationEntryImpl* pending_entry_;
 
-  // currently visible entry
+  // If a new entry fails loading, it is temporarily held here until the error
+  // page is shown.

[Charlie Reis, 2015/04/03 20:59:46]

This needs to mention that it will stick around until the next commit if there
is no error page (e.g., Stop, 204, downloads).

We should also have a TODO with bug # to remove this and find a different way to
match up DidFail to the corresponding error page's DidCommit, because this
approach can't handle navigations in multiple frames.

[Avi (use Gerrit), 2015/04/06 19:38:17]

Done.

+  scoped_ptr<NavigationEntryImpl> failed_pending_entry_;

[Charlie Reis, 2015/04/03 20:59:46]

How bad would it be to store just the things we need from the failed entry?  The
entry is pretty big and (as noted above) it may stick around too long in a lot
of cases.  I'm concerned about things that the entry might be keeping alive,
like site_instance_, source_site_instance_, and  browser_initiated_post_data_.

(This may also make it easier to see what needs to stick around on a per-frame
basis before DidFail and a potential error page DidCommit.)

[Avi (use Gerrit), 2015/04/06 19:38:17]

Done.

+
+  // The index of the currently visible entry.
   int last_committed_entry_index_;
 
-  // index of pending entry if it is in entries_, or -1 if pending_entry_ is a
-  // new entry (created by LoadURL).
+  // The index of the pending entry if it is in entries_, or -1 if
+  // pending_entry_ is a new entry (created by LoadURL).
   int pending_entry_index_;
 
   // The index for the entry that is shown until a navigation occurs.  This is