Remove synchronous compositeAndReadback() from WebLayerTreeView impls.

content/test/web_layer_tree_view_impl_for_testing.cc

Index: content/test/web_layer_tree_view_impl_for_testing.cc
diff --git a/content/test/web_layer_tree_view_impl_for_testing.cc b/content/test/web_layer_tree_view_impl_for_testing.cc
index 28bd7c84a3c68d93936ea6955e323e24019cd6ec..3069317396504b7a4359313b7f1166c8eb3f310f 100644
--- a/content/test/web_layer_tree_view_impl_for_testing.cc
+++ b/content/test/web_layer_tree_view_impl_for_testing.cc
@@ -122,12 +122,6 @@ bool WebLayerTreeViewImplForTesting::commitRequested() const {
 
 void WebLayerTreeViewImplForTesting::didStopFlinging() {}
 
-bool WebLayerTreeViewImplForTesting::compositeAndReadback(
-    void* pixels, const WebRect& rect_in_device_viewport) {
-  return layer_tree_host_->CompositeAndReadback(pixels,
-                                                rect_in_device_viewport);
-}
-
 void WebLayerTreeViewImplForTesting::finishAllRendering() {
   layer_tree_host_->FinishAllRendering();
 }