https://source.android.com/ 
public interface android.webkit.WebChromeClient$CustomViewCallback
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: android.webkit.WebChromeClient$CustomViewCallback
  super_class: java.lang.Object
{
  public abstract void onCustomViewHidden();
    descriptor: ()V
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
}
SourceFile: "WebChromeClient.java"
NestHost: android.webkit.WebChromeClient
InnerClasses:
  public abstract CustomViewCallback = android.webkit.WebChromeClient$CustomViewCallback of android.webkit.WebChromeClient