Add CompositingReasons to compositor layer types.

cc/layers/layer_unittest.cc

Index: cc/layers/layer_unittest.cc
diff --git a/cc/layers/layer_unittest.cc b/cc/layers/layer_unittest.cc
index f087081025bebe1ed84e6f1dfe267ffc1e583417..3814b0a50c4acb602f18b52475de4f9ec65420a1 100644
--- a/cc/layers/layer_unittest.cc
+++ b/cc/layers/layer_unittest.cc
@@ -526,6 +526,8 @@ TEST_F(LayerTest, CheckPropertyChangeCausesCorrectBehavior) {
       gfx::Transform(0.0, 0.0, 0.0, 0.0, 0.0, 0.0)));
   EXPECT_SET_NEEDS_COMMIT(1, test_layer->SetDoubleSided(false));
   EXPECT_SET_NEEDS_COMMIT(1, test_layer->SetDebugName("Test Layer"));
+  EXPECT_SET_NEEDS_COMMIT(1, test_layer->SetCompositingReasons(
+      kCompositingReasonRoot));
   EXPECT_SET_NEEDS_COMMIT(1, test_layer->SetDrawCheckerboardForMissingTiles(
       !test_layer->DrawCheckerboardForMissingTiles()));
   EXPECT_SET_NEEDS_COMMIT(1, test_layer->SetForceRenderSurface(true));