[SPv1] Always set a CompositorElementId on main graphics layers; use PaintLayer id.

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/graphics/CompositorElementId.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 
 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(
+  CompositorElementId element_id = CompositorElementIdFromPaintLayerId(
       1, CompositorElementIdNamespace::kPrimary);
   EXPECT_EQ(1u, IdFromCompositorElementId(element_id));
   EXPECT_EQ(CompositorElementIdNamespace::kPrimary,
             NamespaceFromCompositorElementId(element_id));
 
   element_id = CompositorElementIdFromDOMNodeId(
       1, CompositorElementIdNamespace::kLinkHighlight);
   EXPECT_EQ(1u, IdFromCompositorElementId(element_id));
   EXPECT_EQ(CompositorElementIdNamespace::kLinkHighlight,
             NamespaceFromCompositorElementId(element_id));
 
-  element_id = CompositorElementIdFromDOMNodeId(
-      23, CompositorElementIdNamespace::kScroll);
+  element_id = CompositorElementIdFromScrollbarId(
+      23, CompositorElementIdNamespace::kScrollbar);
   EXPECT_EQ(23u, IdFromCompositorElementId(element_id));
-  EXPECT_EQ(CompositorElementIdNamespace::kScroll,
+  EXPECT_EQ(CompositorElementIdNamespace::kScrollbar,
             NamespaceFromCompositorElementId(element_id));
 }
 
 }  // namespace blink