Mock implementation of overridePreference.

Without this change, the ui_tests cause timeout.
But still failed with it.

BUG=104940
TEST=ui_tests --gtest_filter="*WorkerWebSocket*" --gtest_also_run_disabled_tests


Review URL: http://codereview.chromium.org/8480035

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@110893 0039d316-1c4b-4281-b951-d872f2087c98

chrome/test/data/layout_tests/layout_test_controller.html

@@ -17,6 +17,12 @@ function LayoutTestController() {
     setTimeout(layoutTestController.DelayedNotifyDone1, 0);
   };
 
+  this.overridePreference = function () {
+    // WebSocket tests call this function by preference name
+    // 'WebKitHixie76WebSocketProtocolEnabled' to switch its protocol version.
+    // In Chromium, the value must be 0 because it doesn't support old one.
+  };
+
   this.DelayedNotifyDone1 = function () {
     setTimeout(layoutTestController.DelayedNotifyDone2, 0);
   };