Disable the leak tracking of URLRequests....

base/leak_tracker.h

 // Copyright (c) 2009 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 BASE_LEAK_TRACKER_H_
 #define BASE_LEAK_TRACKER_H_
 
-// Temporarily enable LeakTracker in all builds (both
-// release and debug). This will have an impact on performance, but
-// is intended to help track down a leak which reproduces on dev
-// channel.
-//
-// TODO(eroman): Restore the old code which only enabled LeakTracker
-// for debug builds.
-//
-// http://crbug.com/21199, http://crbug.com/18372
-#ifndef ENABLE_LEAK_TRACKER
+// Only enable leak tracking in debug builds.
+#ifndef NDEBUG
 #define ENABLE_LEAK_TRACKER
 #endif
 
 #ifdef ENABLE_LEAK_TRACKER
 #include "base/debug_util.h"
 #include "base/linked_list.h"
 #include "base/logging.h"
 #endif  // ENABLE_LEAK_TRACKER
 
 // LeakTracker is a helper to verify that all instances of a class
@@ skipping 102 matching lines @@
   }
 
   StackTrace allocation_stack_;
 };
 
 #endif  // ENABLE_LEAK_TRACKER
 
 }  // namespace base
 
 #endif  // BASE_LEAK_TRACKER_H_