cc: Define Region::Contains() to be A contains B if all points in B are also in A.

cc/region_unittest.cc

Index: cc/region_unittest.cc
diff --git a/cc/region_unittest.cc b/cc/region_unittest.cc
index 2fd52d6fb47f65064131ddf69237971ebde360bf..db0fc3c503397b9a54cd711fcea1f4d739beab31 100644
--- a/cc/region_unittest.cc
+++ b/cc/region_unittest.cc
@@ -224,7 +224,10 @@ TEST(RegionTest, ReadPastFullSpanVectorInIntersectsTest) {
   }
 
 TEST(RegionTest, ContainsRegion) {
-  TEST_NO_CONTAINS(gfx::Rect(), gfx::Rect());
+  TEST_CONTAINS(gfx::Rect(), gfx::Rect());
+  TEST_CONTAINS(gfx::Rect(0, 0, 1, 1), gfx::Rect());
+  TEST_CONTAINS(gfx::Rect(10, 10, 1, 1), gfx::Rect());
+
   TEST_NO_CONTAINS(gfx::Rect(), gfx::Rect(0, 0, 1, 1));
   TEST_NO_CONTAINS(gfx::Rect(), gfx::Rect(1, 1, 1, 1));