UserAgent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:56.0) Gecko/20100101 Firefox/56.0

Steps to reproduce the problem:
1. Rewiew the code of ContentViewRenderView::SetCurrentWebContents(
    JNIEnv* env,
    const JavaParamRef<jobject>& obj,
    const JavaParamRef<jobject>& jweb_contents) 
2. Imagine what will happen in further subcalls if web_contents is null. In particular, in method Layer::InsertChild(scoped_refptr<Layer> child, size_t index) we have guaranteed crash on first "child->..."
3. 

What is the expected behavior?

What went wrong?
Program crashes on call to java method ContentViewRenderView.nativeSetCurrentWebContents(long nativeContentViewRenderView, WebContents webContents) if web_contents is null. (For some reason. It's not disalowed case.) 

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 58.2.3029.83  Channel: n/a
OS Version: Ubuntu 16.04
Flash Version: 

I think that "scoped_refptr<cc::Layer>()" should be replased with "cc::Layer::Create()" in method CompositorImpl::SetRootLayer(...