Update {virtual,override} to follow C++11 style in extensions.

extensions/browser/api/usb/usb_apitest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/test/test_utils.h"
 #include "device/usb/usb_service.h"
 #include "extensions/browser/api/device_permissions_prompt.h"
 #include "extensions/browser/api/usb/usb_api.h"
@@ skipping 112 matching lines @@
   MOCK_METHOD2(SetConfiguration,
                void(int configuration_value, const ResultCallback& callback));
   MOCK_METHOD2(ClaimInterface,
                void(int interface_number, const ResultCallback& callback));
   MOCK_METHOD1(ReleaseInterface, bool(int interface_number));
   MOCK_METHOD3(SetInterfaceAlternateSetting,
                void(int interface_number,
                     int alternate_setting,
                     const ResultCallback& callback));
 
-  virtual scoped_refptr<UsbDevice> GetDevice() const override {
-    return device_;
-  }
+  scoped_refptr<UsbDevice> GetDevice() const override { return device_; }
 
   void set_device(UsbDevice* device) { device_ = device; }
 
  protected:
   UsbDevice* device_;
 
   virtual ~MockUsbDeviceHandle() {}
 };
 
 class MockUsbDevice : public UsbDevice {
@@ skipping 190 matching lines @@
 
   TestExtensionsAPIClient test_api_client;
   ASSERT_TRUE(LoadApp("api_test/usb/get_user_selected_devices"));
   ASSERT_TRUE(ready_listener.WaitUntilSatisfied());
 
   mock_service_->NotifyDeviceRemoved(mock_device_);
   ASSERT_TRUE(result_listener.WaitUntilSatisfied());
 }
 
 }  // namespace extensions