Update plugin to handle new style rules for virtual annotations.

tools/clang/plugins/tests/virtual_methods.cpp

-// Copyright (c) 2012 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 "virtual_methods.h"
-
-// Shouldn't warn about method usage in the implementation file.
-class VirtualMethodsInImplementation {
- public:
-  virtual void MethodIsAbstract() = 0;
-  virtual void MethodHasNoArguments();
-  virtual void MethodHasEmptyDefaultImpl() {}
-  virtual bool ComplainAboutThis() { return true; }
-};
-
-// Stubs to fill in the abstract method
-class ConcreteVirtualMethodsInHeaders : public VirtualMethodsInHeaders {
- public:
-  virtual void MethodIsAbstract() override {}
-};
-
-class ConcreteVirtualMethodsInImplementation
-    : public VirtualMethodsInImplementation {
- public:
-  virtual void MethodIsAbstract() override {}
-};
-
-// Fill in the implementations
-void VirtualMethodsInHeaders::MethodHasNoArguments() {}
-void WarnOnMissingVirtual::MethodHasNoArguments() {}
-void VirtualMethodsInImplementation::MethodHasNoArguments() {}
-
-int main() {
-  ConcreteVirtualMethodsInHeaders one;
-  ConcreteVirtualMethodsInImplementation two;
-}