Linux: make compile-time dependency on gnome-keyring optional.

chrome/chrome_browser.gypi

Index: chrome/chrome_browser.gypi
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index e7f007b742f27cdd3f062870b8785c3d5fb686e6..acad48ab4811cda59dfaa193297f40b97771b14b 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -3184,6 +3184,12 @@
             ],
           },
         }],
+        ['use_gnome_keyring==0', {
+          'sources!': [
+            'browser/password_manager/native_backend_gnome_x.h',
+            'browser/password_manager/native_backend_gnome_x.cc',
+          ],
+        }],
         ['touchui==0', {
           'sources!': [
             # Nothing yet.
@@ -3218,7 +3224,7 @@
             'third_party/mozilla_security_manager/nsUsageArrayHelper.h',
           ],
           'conditions': [
-            ['chromeos==0', {
+            ['use_gnome_keyring==1', {
               'dependencies': [
                 '../build/linux/system.gyp:gnome-keyring',
               ],