Stop retrieving scrolling element id from the CompositorElementId.

third_party/WebKit/Source/platform/graphics/CompositorElementIdTest.cpp

Index: third_party/WebKit/Source/platform/graphics/CompositorElementIdTest.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/CompositorElementIdTest.cpp b/third_party/WebKit/Source/platform/graphics/CompositorElementIdTest.cpp
index 16ea792a9b94d5d0f292d18706702dc3220d91c1..2a164b568c08949c8c51da1c15960a9b900ec9bf 100644
--- a/third_party/WebKit/Source/platform/graphics/CompositorElementIdTest.cpp
+++ b/third_party/WebKit/Source/platform/graphics/CompositorElementIdTest.cpp
@@ -10,6 +10,10 @@ namespace blink {
 
 class CompositorElementIdTest : public ::testing::Test {};
 
+uint64_t IdFromCompositorElementId(CompositorElementId element_id) {
+  return element_id.id_ >> kCompositorNamespaceBitCount;
+}
+
 TEST_F(CompositorElementIdTest, EncodeDecode) {
   CompositorElementId element_id = CompositorElementIdFromDOMNodeId(
       1, CompositorElementIdNamespace::kPrimary);