Allow compiling Android with notifications=1, add stubbed UI manager

ui/message_center/message_center.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 118 matching lines @@
         ['use_ash==0', {
           'sources!': [
             'views/message_bubble_base.cc',
             'views/message_bubble_base.h',
             'views/message_center_bubble.cc',
             'views/message_center_bubble.h',
             'views/message_popup_bubble.cc',
             'views/message_popup_bubble.h',
           ],
         }],
-        ['notifications==0', {  # Android and iOS.
+        # iOS disables notifications altogether, Android implements its own
+        # notification UI manager instead of deferring to the message center.
+        ['notifications==0 or OS=="android"', {
           'sources/': [
             # Exclude everything except dummy impl.
             ['exclude', '\\.(cc|mm)$'],
             ['include', '^dummy_message_center\\.cc$'],
             ['include', '^message_center_switches\\.cc$'],
           ],
         }, {  # notifications==1
           'sources!': [ 'dummy_message_center.cc' ],
         }],
+        # Include a minimal set of files required for notifications on Android.
+        ['OS=="android"', {
+          'sources/': [
+            ['include', '^notification\\.cc$'],
+            ['include', '^notification_delegate\\.cc$'],
+            ['include', '^notifier_settings\\.cc$'],
+          ],
+        }],
       ],
     },  # target_name: message_center
     {
       'target_name': 'message_center_test_support',
       'type': 'static_library',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../base/base.gyp:test_support_base',
         '../../skia/skia.gyp:skia',
         '../base/ui_base.gyp:ui_base',
@@ skipping 73 matching lines @@
         # TODO(dmikurube): Kill linux_use_tcmalloc. http://crbug.com/345554
         ['OS=="linux" and ((use_allocator!="none" and use_allocator!="see_use_tcmalloc") or (use_allocator=="see_use_tcmalloc" and linux_use_tcmalloc==1))', {
           'dependencies': [
             '../../base/allocator/allocator.gyp:allocator',
           ],
         }],
       ],
     },  # target_name: message_center_unittests
   ],
 }