Give the JS dialog manager the alerting frame.

https://chromium-review.googlesource.com/c/chromium/src/+/928828
https://chromium-review.googlesource.com/c/chromium/src/+/791517

atom/browser/atom_javascript_dialog_manager.cc

@@ -33,12 +33,13 @@ AtomJavaScriptDialogManager::~AtomJavaScriptDialogManager() = default;
 
 void AtomJavaScriptDialogManager::RunJavaScriptDialog(
     content::WebContents* web_contents,
-    const GURL& origin_url,
+    content::RenderFrameHost* rfh,
     JavaScriptDialogType dialog_type,
     const base::string16& message_text,
     const base::string16& default_prompt_text,
     DialogClosedCallback callback,
     bool* did_suppress_message) {
+  auto origin_url = rfh->GetLastCommittedURL();
   const std::string& origin = origin_url.GetOrigin().spec();
   if (origin_counts_[origin] == kUserWantsNoMoreDialogs) {
     return std::move(callback).Run(false, base::string16());
@@ -84,6 +85,7 @@ void AtomJavaScriptDialogManager::RunJavaScriptDialog(
 
 void AtomJavaScriptDialogManager::RunBeforeUnloadDialog(
     content::WebContents* web_contents,
+    content::RenderFrameHost* rfh,
     bool is_reload,
     DialogClosedCallback callback) {
   bool default_prevented = api_web_contents_->Emit("will-prevent-unload");

atom/browser/atom_javascript_dialog_manager.h

@@ -23,13 +23,14 @@ class AtomJavaScriptDialogManager : public content::JavaScriptDialogManager {
 
   // content::JavaScriptDialogManager implementations.
   void RunJavaScriptDialog(content::WebContents* web_contents,
-                           const GURL& origin_url,
+                           content::RenderFrameHost* rfh,
                            content::JavaScriptDialogType dialog_type,
                            const base::string16& message_text,
                            const base::string16& default_prompt_text,
                            DialogClosedCallback callback,
                            bool* did_suppress_message) override;
   void RunBeforeUnloadDialog(content::WebContents* web_contents,
+                             content::RenderFrameHost* rfh,
                              bool is_reload,
                              DialogClosedCallback callback) override;
   void CancelDialogs(content::WebContents* web_contents,