Add "clear" to about://instant.

chrome/browser/instant/instant_controller.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_INSTANT_INSTANT_CONTROLLER_H_
 #define CHROME_BROWSER_INSTANT_INSTANT_CONTROLLER_H_
 
 #include <list>
 #include <map>
 #include <string>
@@ skipping 156 matching lines @@
 
   // Called when the |overlay_| might be stale. If it's actually stale, and the
   // omnibox doesn't have focus, and the overlay isn't showing, the |overlay_|
   // is deleted and recreated. Else the refresh is skipped.
   void ReloadOverlayIfStale();
 
   // Adds a new event to |debug_events_| and also DVLOG's it. Ensures that
   // |debug_events_| doesn't get too large.
   void LogDebugEvent(const std::string& info) const;
 
+  // Resets list of debug events.
+  void ClearDebugEvents();
+
   // See comments for |debug_events_| below.
   const std::list<std::pair<int64, std::string> >& debug_events() {
     return debug_events_;
   }
 
   // Returns the transition type of the last AutocompleteMatch passed to Update.
   content::PageTransition last_transition_type() const {
     return last_transition_type_;
   }
 
@@ skipping 254 matching lines @@
   // Used for Top Sites async retrieval.
   base::WeakPtrFactory<InstantController> weak_ptr_factory_;
 
   // Used to get notifications about Most Visted changes.
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(InstantController);
 };
 
 #endif  // CHROME_BROWSER_INSTANT_INSTANT_CONTROLLER_H_