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

third_party/WebKit/Source/platform/graphics/CompositorMutableStateProvider.h

 // 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.
 
 #ifndef CompositorMutableStateProvider_h
 #define CompositorMutableStateProvider_h
 
-#include "platform/PlatformExport.h"
 #include <cstdint>
 #include <memory>
+#include "platform/PlatformExport.h"
+#include "platform/graphics/CompositorElementId.h"
 
 namespace cc {
 class LayerTreeImpl;
 }  // namespace cc
 
 namespace blink {
 
 class CompositorMutableState;
 struct CompositorMutations;
 
 // This class is a window onto compositor-owned state. It vends out wrappers
 // around per-element bits of this state.
 class PLATFORM_EXPORT CompositorMutableStateProvider {
  public:
   CompositorMutableStateProvider(cc::LayerTreeImpl*, CompositorMutations*);
   ~CompositorMutableStateProvider();
 
-  std::unique_ptr<CompositorMutableState> GetMutableStateFor(
-      uint64_t element_id);
+  std::unique_ptr<CompositorMutableState> GetMutableStateFor(DOMNodeId);
 
  private:
   cc::LayerTreeImpl* tree_;
   CompositorMutations* mutations_;
 };
 
 }  // namespace blink
 
 #endif  // CompositorMutableStateProvider_h