Mock implementation of overridePreference.

chrome/test/data/layout_tests/layout_test_controller.html

Index: chrome/test/data/layout_tests/layout_test_controller.html
diff --git a/chrome/test/data/layout_tests/layout_test_controller.html b/chrome/test/data/layout_tests/layout_test_controller.html
index e2bf813195ed0e9617001cfbfd6d2667d1615cf0..198c3853340a4032ffa22b4453762299c510a441 100644
--- a/chrome/test/data/layout_tests/layout_test_controller.html
+++ b/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);
   };