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, IntersectedRectProtoConversion) {
+  Region region(gfx::Rect(0, 0, 10, 10));
+  region.Intersect(gfx::Rect(0, 0, 5, 5));
+  VerifySerializeAndDeserializeProto(region);
+}

[vmpstr, 2015/11/23 21:10:04]

If you have a region that's constructed as a union of two overlapping rects,
does that pass the test?

[nyquist, 2015/11/23 22:31:29]

Yes, that works. Added test for this. Thanks!

How these rects are supposed to work is not totally clear to me, so please tell
me if there are more tests you think would be helpful.

+
+}  // namespace
+}  // namespace cc