Enable hidpi on Linux, refactor a bit on Windows to share

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 142 matching lines @@
         'color_profile_mac.mm',
         'color_profile_win.cc',
         'color_utils.cc',
         'color_utils.h',
         'display.cc',
         'display.h',
         'display_change_notifier.cc',
         'display_change_notifier.h',
         'display_observer.cc',
         'display_observer.h',
+        'dpi.cc',
+        'dpi.h',
         'favicon_size.cc',
         'favicon_size.h',
         'font.cc',
         'font.h',
         'font_fallback.h',
         'font_fallback_linux.cc',
         'font_fallback_mac.cc',
         'font_fallback_win.cc',
         'font_fallback_win.h',
         'font_list.cc',
@@ skipping 123 matching lines @@
         'transform.cc',
         'transform.h',
         'transform_util.cc',
         'transform_util.h',
         'ui_gfx_exports.cc',
         'utf16_indexing.cc',
         'utf16_indexing.h',
         'vsync_provider.h',
         'win/direct_write.cc',
         'win/direct_write.h',
-        'win/dpi.cc',
-        'win/dpi.h',
         'win/hwnd_util.cc',
         'win/hwnd_util.h',
         'win/scoped_set_map_mode.h',
         'win/singleton_hwnd.cc',
         'win/singleton_hwnd.h',
         'win/window_impl.cc',
         'win/window_impl.h',
       ],
       'includes': [
         '../../build/android/increase_size_for_speed.gypi',
@@ skipping 95 matching lines @@
             'platform_font_ozone.cc',
             'render_text_ozone.cc',
           ],
         }],
         ['desktop_linux==1 or chromeos==1', {
           'dependencies': [
             # font_render_params_linux.cc uses fontconfig
             '<(DEPTH)/build/linux/system.gyp:fontconfig',
           ],
         }],
+        ['desktop_linux!=1 and OS!="win"', {
+          'sources!': [
+            'dpi.cc',
+          ],
+        }],
       ],
       'target_conditions': [
         # Need 'target_conditions' to override default filename_rules to include
         # the file on iOS.
         ['OS == "ios"', {
           'sources/': [
             ['include', '^scoped_cg_context_save_gstate_mac\\.h$'],
           ],
         }],
       ],
@@ skipping 53 matching lines @@
          ],
          'variables': {
            'jni_gen_package': 'ui/gfx',
          },
          'includes': [ '../../build/jni_generator.gypi' ],
        },
      ],
     }],
   ],
 }