Remove parts of //cc we aren't using

cc/base/invalidation_region.h

-// Copyright 2013 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.
-
-#ifndef CC_BASE_INVALIDATION_REGION_H_
-#define CC_BASE_INVALIDATION_REGION_H_
-
-#include "cc/base/cc_export.h"
-#include "cc/base/region.h"
-#include "ui/gfx/geometry/rect.h"
-
-namespace cc {
-
-// This class behaves similarly to Region, but it may have false positives. That
-// is, InvalidationRegion can be simplified to encompass a larger area than the
-// collection of rects unioned.
-class CC_EXPORT InvalidationRegion {
- public:
-  InvalidationRegion();
-  ~InvalidationRegion();
-
-  void Swap(Region* region);
-  void Clear();
-  void Union(const gfx::Rect& rect);
-  bool IsEmpty() const { return region_.IsEmpty(); }
-
- private:
-  void SimplifyIfNeeded();
-
-  Region region_;
-};
-
-}  // namespace cc
-
-#endif  // CC_BASE_INVALIDATION_REGION_H_