Added default implementations of GetAcceleratorForCommandId.

ui/base/cocoa/menu_controller_unittest.mm

Index: ui/base/cocoa/menu_controller_unittest.mm
diff --git a/ui/base/cocoa/menu_controller_unittest.mm b/ui/base/cocoa/menu_controller_unittest.mm
index 138c112a8cad8b7b22134419840e6eec7e4e8da9..e49904ab02dc3a76b63752256af1575d3b466066 100644
--- a/ui/base/cocoa/menu_controller_unittest.mm
+++ b/ui/base/cocoa/menu_controller_unittest.mm
@@ -45,10 +45,6 @@ class Delegate : public SimpleMenuModel::Delegate {
     ++enable_count_;
     return true;
   }
-  bool GetAcceleratorForCommandId(int command_id,
-                                  Accelerator* accelerator) const override {
-    return false;
-  }
   void ExecuteCommand(int command_id, int event_flags) override {
     ++execute_count_;
   }