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..e89cf30419943e302006b80f5088240918a568f5 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(20));

[suzyh_UTC10 (ex-contributor), 2017/05/05 04:27:30]

Typo '20' instead of '2'?

[chrishtr, 2017/05/05 05:34:52]

It wasn't a typo, because 2 is apparently what it was before this
line, so the "change of property" didn't get exercised. Changed
it to 3 for a bit better clarity.

   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(2));
   VERIFY_NO_NEEDS_UPDATE_DRAW_PROPERTIES(
       layer->SetMutableProperties(MutableProperty::kTransform));
 }