Add cross-platform API to get the form factor of the device

ui/ui.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,
   },
   'includes': [
     'ui_resources.gypi',
@@ skipping 127 matching lines @@
         'base/cursor/cursor_loader_win.h',
         'base/cursor/cursor_loader_x11.cc',
         'base/cursor/cursor_loader_x11.h',
         'base/cursor/cursor_win.cc',
         'base/cursor/cursor_x11.cc',
         'base/cursor/cursors_aura.cc',
         'base/cursor/cursors_aura.h',
         'base/default_theme_provider.cc',
         'base/default_theme_provider.h',
         'base/default_theme_provider_mac.mm',
+        'base/device_form_factor_android.cc',
+        'base/device_form_factor_desktop.cc',
+        'base/device_form_factor_ios.mm',
+        'base/device_form_factor.h',
         'base/dragdrop/cocoa_dnd_util.h',
         'base/dragdrop/cocoa_dnd_util.mm',
         'base/dragdrop/drag_drop_types.h',
         'base/dragdrop/drag_drop_types_win.cc',
         'base/dragdrop/drag_source_win.cc',
         'base/dragdrop/drag_source_win.h',
         'base/dragdrop/drag_utils.cc',
         'base/dragdrop/drag_utils.h',
         'base/dragdrop/drag_utils_aura.cc',
         'base/dragdrop/drag_utils_win.cc',
@@ skipping 402 matching lines @@
             'libraries': [
               '-ljnigraphics',
             ],
           },
         }],
         ['OS=="android" and android_webview_build==0', {
           'dependencies': [
             'ui_java',
           ],
         }],
+        ['OS=="android" or OS=="ios"', {
+          'sources!': [
+            'base/device_form_factor_desktop.cc'
+          ],
+        }],
         ['OS=="linux"', {
           'libraries': [
             '-ldl',
           ],
         }],
         ['use_system_icu==1', {
           # When using the system icu, the icu targets generate shim headers
           # which are included by public headers in the ui target, so we need
           # ui to be a hard dependency for all its users.
           'hard_dependency': 1,
@@ skipping 140 matching lines @@
               'xcode_settings': {
                 'GCC_SYMBOLS_PRIVATE_EXTERN': 'NO',
               },
             }],
           ],
         },
       ],
     }],
   ],
 }