Move prerender histograms out of prerender manager.

chrome/chrome_browser.gypi

 # Copyright (c) 2011 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.
 
 {
   'targets': [
     {
       'target_name': 'browser',
       'type': 'static_library',
       'dependencies': [
@@ skipping 1735 matching lines @@
         'browser/prefs/value_map_pref_store.h',
         'browser/prerender/prerender_condition.h',
         'browser/prerender/prerender_config.cc',
         'browser/prerender/prerender_config.h',
         'browser/prerender/prerender_contents.cc',
         'browser/prerender/prerender_contents.h',
         'browser/prerender/prerender_field_trial.cc',
         'browser/prerender/prerender_field_trial.h',
         'browser/prerender/prerender_final_status.cc',
         'browser/prerender/prerender_final_status.h',
+        'browser/prerender/prerender_histograms.cc',
+        'browser/prerender/prerender_histograms.h',
         'browser/prerender/prerender_history.cc',
         'browser/prerender/prerender_history.h',
         'browser/prerender/prerender_manager.cc',
         'browser/prerender/prerender_manager.h',
         'browser/prerender/prerender_observer.cc',
         'browser/prerender/prerender_observer.h',
         'browser/prerender/prerender_origin.cc',
         'browser/prerender/prerender_origin.h',
         'browser/prerender/prerender_render_view_host_observer.cc',
         'browser/prerender/prerender_render_view_host_observer.h',
@@ skipping 3197 matching lines @@
               # weak imports in dependents, who still must #include
               # closure_blocks_leopard_compat.h to get weak imports.
               'type': 'none',
             }],
           ],
         },
       ],
     }],
   ],
 }