x11: Include X11 dependencies only when building with X11.

base/base.gyp

Index: base/base.gyp
diff --git a/base/base.gyp b/base/base.gyp
index 8118d87a54a29f54f799d41e578a9e7d6643ef14..54cd07c05ee722d26427cdcedd4ae0c4841d4a45 100644
--- a/base/base.gyp
+++ b/base/base.gyp
@@ -62,7 +62,6 @@
           'dependencies': [
             'symbolize',
             '../build/linux/system.gyp:glib',
-            '../build/linux/system.gyp:x11',
             'xdg_mime',
           ],
           'defines': [
@@ -73,7 +72,6 @@
           ],
           'export_dependent_settings': [
             '../build/linux/system.gyp:glib',
-            '../build/linux/system.gyp:x11',
           ],
         }, {  # use_glib!=1
             'sources/': [
@@ -81,6 +79,14 @@
               ['exclude', '_nss\\.cc$'],
             ],
         }],
+        ['use_x11==1', {
+          'dependencies': [
+            '../build/linux/system.gyp:x11',
+          ],
+          'export_dependent_settings': [
+            '../build/linux/system.gyp:x11',
+          ],
+        }],
         ['OS == "android" and _toolset == "host"', {
           # Base for host support is the minimum required to run the
           # ssl false start blacklist tool. It requires further changes