[DevTools] Use WebLayerTreeView::layerTreeId() for instrumentation.

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 4233 matching lines @@
         m_layerTreeView->detachCompositorAnimationTimeline(timeline);
 }
 
 void WebViewImpl::initializeLayerTreeView()
 {
     if (m_client) {
         m_client->initializeLayerTreeView();
         m_layerTreeView = m_client->layerTreeView();
     }
 
+    if (WebDevToolsAgentImpl* devTools = mainFrameDevToolsAgentImpl())
+        devTools->layerTreeViewChanged(m_layerTreeView);
+
     m_page->settings().setAcceleratedCompositingEnabled(m_layerTreeView != 0);
 
     // FIXME: only unittests, click to play, Android priting, and printing (for headers and footers)
     // make this assert necessary. We should make them not hit this code and then delete allowsBrokenNullLayerTreeView.
     ASSERT(m_layerTreeView || !m_client || m_client->allowsBrokenNullLayerTreeView());
 }
 
 void WebViewImpl::setIsAcceleratedCompositingActive(bool active)
 {
     // In the middle of shutting down; don't try to spin back up a compositor.
@@ skipping 242 matching lines @@
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 void WebViewImpl::forceNextWebGLContextCreationToFail()
 {
     WebGLRenderingContext::forceNextWebGLContextCreationToFail();
 }
 
 } // namespace blink