aura: Make the Linux version of IconLoader not require GTK+.

build/common.gypi

 # Copyright (c) 2011 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1260 matching lines @@
                           ['exclude', '\\.mm?$' ] ],
           }],
           ['use_x11!=1', {
             'sources/': [
               ['exclude', '_(chromeos|x|x11)(_unittest)?\\.(h|cc)$'],
               ['exclude', '(^|/)x11_[^/]*\\.(h|cc)$'],
             ],
           }],
           ['toolkit_uses_gtk!=1', {
             'sources/': [
-              ['exclude', '_(gtk|xdg)(_unittest)?\\.(h|cc)$'],
+              ['exclude', '_gtk(_unittest)?\\.(h|cc)$'],
               ['exclude', '(^|/)gtk/'],
               ['exclude', '(^|/)gtk_[^/]*\\.(h|cc)$'],
             ],
           }],
+          ['OS!="linux"', {
+            'sources/': [
+              ['exclude', '_xdg(_unittest)?\\.(h|cc)$'],
+            ],
+          }],
           ['use_wayland!=1', {
             'sources/': [
               ['exclude', '_(wayland)(_unittest)?\\.(h|cc)$'],
               ['exclude', '(^|/)wayland/'],
               ['exclude', '(^|/)(wayland)_[^/]*\\.(h|cc)$'],
             ],
           }],
           # Do not exclude the linux files on OpenBSD since most of them can be
           # shared at this point.
           # In case a file is not needed, it is going to be excluded later on.
@@ skipping 1328 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }