Change cc::ElementId to be a uint64_t

cc/layers/layer_impl_unittest.cc

Index: cc/layers/layer_impl_unittest.cc
diff --git a/cc/layers/layer_impl_unittest.cc b/cc/layers/layer_impl_unittest.cc
index f8f55537c48a92033f2e319478e6e70ae3c28a08..089119f5e79a0ed1b270190400de5d5c82c744af 100644
--- a/cc/layers/layer_impl_unittest.cc
+++ b/cc/layers/layer_impl_unittest.cc
@@ -225,7 +225,7 @@ TEST(LayerImplTest, VerifyLayerChangesAreTrackedProperly) {
   // Changing these properties does not cause the layer to be marked as changed
   // but does cause the layer to need to push properties.
   EXECUTE_AND_VERIFY_NEEDS_PUSH_PROPERTIES_AND_SUBTREE_DID_NOT_CHANGE(
-      root->SetElementId(ElementId(2, 0)));
+      root->SetElementId(ElementId(2)));
   EXECUTE_AND_VERIFY_NEEDS_PUSH_PROPERTIES_AND_SUBTREE_DID_NOT_CHANGE(
       root->SetMutableProperties(MutableProperty::kOpacity);
       root->SetNeedsPushProperties());
@@ -349,7 +349,7 @@ TEST(LayerImplTest, VerifyNeedsUpdateDrawProperties) {
   VERIFY_NO_NEEDS_UPDATE_DRAW_PROPERTIES(
       layer->SetBackgroundColor(arbitrary_color));
   VERIFY_NO_NEEDS_UPDATE_DRAW_PROPERTIES(layer->SetBounds(arbitrary_size));
-  VERIFY_NO_NEEDS_UPDATE_DRAW_PROPERTIES(layer->SetElementId(ElementId(2, 0)));
+  VERIFY_NO_NEEDS_UPDATE_DRAW_PROPERTIES(layer->SetElementId(ElementId(2)));
   VERIFY_NO_NEEDS_UPDATE_DRAW_PROPERTIES(
       layer->SetMutableProperties(MutableProperty::kTransform));
 }