Add support for converting cc::Region to and from protobuf.

cc/proto/cc_conversions_unittest.cc

+// Copyright 2015 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/proto/cc_conversions.h"
+
+#include "cc/base/region.h"
+#include "cc/proto/region.pb.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/geometry/rect.h"
+
+namespace cc {
+namespace {
+
+void VerifySerializeAndDeserializeProto(const Region& region1) {
+  proto::Region proto;
+  RegionToProto(region1, &proto);
+  Region region2 = RegionFromProto(proto);
+  EXPECT_EQ(region1, region2);
+}
+
+TEST(RegionTest, SingleRectProtoConversion) {
+  Region region(gfx::Rect(14, 15, 16, 17));
+  VerifySerializeAndDeserializeProto(region);
+}
+
+TEST(RegionTest, MultipleRectProtoConversion) {
+  Region region(gfx::Rect(0, 0, 1, 1));
+  region.Union(gfx::Rect(9, 0, 1, 1));
+  region.Union(gfx::Rect(0, 9, 1, 1));
+  region.Union(gfx::Rect(9, 9, 1, 1));
+  VerifySerializeAndDeserializeProto(region);
+}
+
+TEST(RegionTest, OverlappingRectIntersectProtoConversion) {
+  Region region(gfx::Rect(0, 0, 10, 10));
+  region.Intersect(gfx::Rect(5, 5, 10, 10));
+  VerifySerializeAndDeserializeProto(region);
+}
+
+TEST(RegionTest, OverlappingRectUnionProtoConversion) {

[vmpstr, 2015/11/23 23:09:20]

I'd also add one

Region region(gfx::Rect(0, 0, 10, 10));
region.Subtract(gfx::Rect(5, 5, 1, 1));

[nyquist, 2015/11/23 23:37:35]

Done.

+  Region region(gfx::Rect(0, 0, 10, 10));
+  region.Union(gfx::Rect(5, 5, 10, 10));
+  VerifySerializeAndDeserializeProto(region);
+}
+
+}  // namespace
+}  // namespace cc