Add metrics for the number of attached displays.

ui/gfx/gfx.gyp

 # Copyright (c) 2013 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 333 matching lines @@
             'icon_util.h',
           ],
           # TODO(jschuh): C4267: http://crbug.com/167187 size_t -> int
           # C4324 is structure was padded due to __declspec(align()), which is
           # uninteresting.
           'msvs_disabled_warnings': [ 4267, 4324 ],
         }],
         ['OS=="android"', {
           'sources!': [
             'animation/throb_animation.cc',
-            'display_observer.cc',
             'selection_model.cc',
           ],
           'dependencies': [
             'gfx_jni_headers',
           ],
           'link_settings': {
             'libraries': [
               '-landroid',
               '-ljnigraphics',
             ],
@@ skipping 116 matching lines @@
          ],
          'variables': {
            'jni_gen_package': 'ui/gfx',
          },
          'includes': [ '../../build/jni_generator.gypi' ],
        },
      ],
     }],
   ],
 }