Make RenderWidget responsible for the composited view's lifetime

content/renderer/render_widget.h

Index: content/renderer/render_widget.h
diff --git a/content/renderer/render_widget.h b/content/renderer/render_widget.h
index 02b03b1b705012e7aed9edee1717fe84b31882cf..c0cbd1eccb9e2837d44e3ada325e224a018c2c58 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -32,6 +32,7 @@
 #include "ui/gfx/rect.h"
 #include "ui/gfx/vector2d.h"
 #include "ui/surface/transport_dib.h"
+#include "webkit/compositor_bindings/web_layer_tree_view_impl.h"
 #include "webkit/glue/webcursor.h"
 
 struct ViewHostMsg_UpdateRect_Params;
@@ -121,6 +122,11 @@ class CONTENT_EXPORT RenderWidget
   virtual void didAutoResize(const WebKit::WebSize& new_size);
   virtual void didActivateCompositor(int input_handler_identifier);
   virtual void didDeactivateCompositor();
+  virtual void initializeLayerTreeView(
+      WebKit::WebLayerTreeViewClient* client,
+      const WebKit::WebLayer& root_layer,
+      const WebKit::WebLayerTreeView::Settings& settings);
+  virtual WebKit::WebLayerTreeView* layerTreeView();
   virtual void didBecomeReadyForAdditionalInput();
   virtual void didCommitAndDrawCompositorFrame();
   virtual void didCompleteSwapBuffers();
@@ -450,6 +456,9 @@ class CONTENT_EXPORT RenderWidget
   // We are responsible for destroying this object via its Close method.
   WebKit::WebWidget* webwidget_;
 
+  // This is lazily constructed and must not outlive webwidget_.
+  scoped_ptr<WebKit::WebLayerTreeViewImpl> web_layer_tree_view_;
+
   // Set to the ID of the view that initiated creating this view, if any. When
   // the view was initiated by the browser (the common case), this will be
   // MSG_ROUTING_NONE. This is used in determining ownership when opening