Version: v5.0.5, v5.0.6
JavaScript code: `document.querySelector('iframe').contentWindow.print()`
shell/browser/api/atom_api_web_contents.cc
content::RenderFrameHost* render_frame_host) {
  if (!render_frame_host->GetParent())
    Emit("dom-ready");
}
void WebContents::DidFinishLoad(content::RenderFrameHost* render_frame_host,
                                const GURL& validated_url) {
  bool is_main_frame = !render_frame_host->GetParent();
  int frame_process_id = render_frame_host->GetProcess()->GetID();
  int frame_routing_id = render_frame_host->GetRoutingID();
  Emit("did-frame-finish-load", is_main_frame, frame_process_id,
       frame_routing_id);
  if (is_main_frame)
    Emit("did-finish-load");
}
void WebContents::DidFailLoad(content::RenderFrameHost* render_frame_host,
                              const GURL& url,
                              int error_code,
                              const base::string16& error_description) {
  bool is_main_frame = !render_frame_host->GetParent();
  int frame_process_id = render_frame_host->GetProcess()->GetID();
  int frame_routing_id = render_frame_host->GetRoutingID();
  Emit("did-fail-load", error_code, error_description, url, is_main_frame,
       frame_process_id, frame_routing_id);
}
void WebContents::DidStartLoading() {
  Emit("did-start-loading");
}
void WebContents::DidStopLoading() {