Consider an immediate redirect as machine-initiated and slow one as...

chrome/browser/tab_contents/navigation_controller.h

Index: chrome/browser/tab_contents/navigation_controller.h
===================================================================
--- chrome/browser/tab_contents/navigation_controller.h	(revision 17847)
+++ chrome/browser/tab_contents/navigation_controller.h	(working copy)
@@ -11,6 +11,7 @@
 
 #include "base/linked_ptr.h"
 #include "base/string16.h"
+#include "base/time.h"
 #include "googleurl/src/gurl.h"
 #include "chrome/browser/sessions/session_id.h"
 #include "chrome/browser/ssl/ssl_manager.h"
@@ -288,6 +289,12 @@
     return tab_contents_;
   }
 
+  // Called when a document has been loaded in a frame.
+  void DocumentLoadedInFrame();
+
+  // Called when the user presses the mouse, enter key or space bar.
+  void OnUserGesture();
+
   // For use by TabContents ----------------------------------------------------
 
   // Handles updating the navigation state after the renderer has navigated.
@@ -432,6 +439,13 @@
   // Discards the transient entry.
   void DiscardTransientEntry();
 
+  // Returns true if the navigation is redirect.
+  bool IsRedirect(const ViewHostMsg_FrameNavigate_Params& params);
+
+  // Returns true if the navigation is likley to be automatic rather than
+  // user-initiated.
+  bool IsLikelyAutoNavigation(base::TimeTicks now);
+
   // ---------------------------------------------------------------------------
 
   // The user profile associated with this controller
@@ -491,6 +505,12 @@
   // Unique identifier of the window we're in. Used by session restore.
   SessionID window_id_;
 
+  // The time ticks at which the last document was loaded.
+  base::TimeTicks last_document_loaded_;
+
+  // Whether a user gesture has been observed since the last navigation.
+  bool user_gesture_observed_;
+
   // Should Reload check for post data? The default is true, but is set to false
   // when testing.
   static bool check_for_repost_;