added gpu_benchmarking_extension boilerplate and hooked it up to a new switch.

content/content_renderer.gypi

 # Copyright (c) 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.
 
 {
   'dependencies': [
     '../jingle/jingle.gyp:jingle_glue',
     '../net/net.gyp:net',
     '../ppapi/ppapi_internal.gyp:ppapi_proxy',
     '../ppapi/ppapi_internal.gyp:ppapi_shared',
@@ skipping 59 matching lines @@
     'renderer/external_popup_menu.cc',
     'renderer/external_popup_menu.h',
     'renderer/gamepad_shared_memory_reader.cc',
     'renderer/gamepad_shared_memory_reader.h',
     'renderer/geolocation_dispatcher.cc',
     'renderer/geolocation_dispatcher.h',
     'renderer/gpu/compositor_thread.cc',
     'renderer/gpu/compositor_thread.h',
     'renderer/gpu/input_event_filter.cc',
     'renderer/gpu/input_event_filter.h',
+    'renderer/gpu_benchmarking_extension.cc',
+    'renderer/gpu_benchmarking_extension.h',
     'renderer/idle_user_detector.cc',
     'renderer/idle_user_detector.h',
     'renderer/input_tag_speech_dispatcher.cc',
     'renderer/input_tag_speech_dispatcher.h',
     'renderer/java/java_bridge_channel.cc',
     'renderer/java/java_bridge_channel.h',
     'renderer/java/java_bridge_dispatcher.cc',
     'renderer/java/java_bridge_dispatcher.h',
     'renderer/load_progress_tracker.cc',
     'renderer/load_progress_tracker.h',
@@ skipping 228 matching lines @@
     }, {
       'sources!': [
         'renderer/java/java_bridge_channel.cc',
         'renderer/java/java_bridge_channel.h',
         'renderer/java/java_bridge_dispatcher.cc',
         'renderer/java/java_bridge_dispatcher.h',
       ],
     }],
   ],
 }