Remove parts of //cc we aren't using

cc/base/invalidation_region.cc

-// 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.
-
-#include "cc/base/invalidation_region.h"
-
-#include "base/metrics/histogram.h"
-
-namespace {
-
-const int kMaxInvalidationRectCount = 256;
-
-}  // namespace
-
-namespace cc {
-
-InvalidationRegion::InvalidationRegion() {}
-
-InvalidationRegion::~InvalidationRegion() {}
-
-void InvalidationRegion::Swap(Region* region) {
-  region_.Swap(region);
-}
-
-void InvalidationRegion::Clear() {
-  region_.Clear();
-}
-
-void InvalidationRegion::Union(const gfx::Rect& rect) {
-  region_.Union(rect);
-  SimplifyIfNeeded();
-}
-
-void InvalidationRegion::SimplifyIfNeeded() {
-  if (region_.GetRegionComplexity() > kMaxInvalidationRectCount)
-    region_ = region_.bounds();
-}
-
-}  // namespace cc