Linux: add gyp rules for gio library and gsettings link mode.

These will be used to add support for proxy settings in gsettings.
Note that no new dependencies are added in the default configuration.
BUG=80453

Review URL: http://codereview.chromium.org/7030007

git-svn-id: http://src.chromium.org/svn/trunk/src/build@85524 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -361,6 +361,8 @@
 
     # Set to 1 to link against libgnome-keyring instead of using dlopen().
     'linux_link_gnome_keyring%': 0,
+    # Set to 1 to link against gsettings APIs instead of using dlopen().
+    'linux_link_gsettings%': 0,
 
     # Used to disable Native Client at compile time, for platforms where it
     # isn't supported
@@ -519,11 +521,14 @@
         'libjpeg_gyp_path': '../third_party/libjpeg/libjpeg.gyp',
       }],  # use_libjpeg_turbo==1
 
-      # Use GConf, the GNOME configuration system.
+      # Options controlling the use of GConf (the classic GNOME configuration
+      # system) and GIO, which contains GSettings (the new GNOME config system).
       ['chromeos==1', {
         'use_gconf%': 0,
+        'use_gio%': 0,
       }, {
         'use_gconf%': 1,
+        'use_gio%': 1,
       }],
 
       # Set up -D and -E flags passed into grit.

linux/system.gyp

@@ -211,6 +211,41 @@
           },
       }]]
     },
+    {
+      'target_name': 'gio',
+      'type': 'settings',
+      'conditions': [
+        ['use_gio==1 and _toolset=="target"', {
+          'direct_dependent_settings': {
+            'cflags': [
+              '<!@(<(pkg-config) --cflags gio-2.0)',
+            ],
+            'defines': [
+              'USE_GIO',
+            ],
+            'conditions': [
+              ['linux_link_gsettings==0', {
+                'defines': ['DLOPEN_GSETTINGS'],
+              }],
+            ],
+          },
+          'link_settings': {
+            'ldflags': [
+              '<!@(<(pkg-config) --libs-only-L --libs-only-other gio-2.0)',
+            ],
+            'libraries': [
+              '<!@(<(pkg-config) --libs-only-l gio-2.0)',
+            ],
+            'conditions': [
+              ['linux_link_gsettings==0', {
+                'libraries': [
+                  '-ldl',
+                ],
+              }],
+            ],
+          },
+      }]]
+    },
     {
       'target_name': 'x11',
       'type': 'settings',