Remove synchronous compositeAndReadback() from WebLayerTreeView impls.

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index 9ea0cda8885bcd5dc0e1d0b54b0bf1f3a0d5f957..cc7fc98999a757d3282a82017e07fa3f82fae59b 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -559,12 +559,6 @@ void RenderWidgetCompositor::clearViewportLayers() {
                                            scoped_refptr<cc::Layer>());
 }
 
-bool RenderWidgetCompositor::compositeAndReadback(
-    void *pixels, const WebRect& rect_in_device_viewport) {
-  return layer_tree_host_->CompositeAndReadback(pixels,
-                                                rect_in_device_viewport);
-}
-
 void CompositeAndReadbackAsyncCallback(
     blink::WebCompositeAndReadbackAsyncCallback* callback,
     scoped_ptr<cc::CopyOutputResult> result) {