Cancel JavaScript dialogs when an interstitial appears.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 5c51c153a666b65d41ff53407549e563c1b06a63..9c42e7c231561d0b913bac0799305fab369e1446 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1785,6 +1785,12 @@ void WebContentsImpl::AttachInterstitialPage(
     InterstitialPageImpl* interstitial_page) {
   DCHECK(interstitial_page);
   render_manager_.set_interstitial_page(interstitial_page);
+
+  // Cancel any visible dialogs so that they don't interfere with the
+  // interstitial.
+  if (dialog_manager_)
+    dialog_manager_->CancelActiveAndPendingDialogs(this);
+
   FOR_EACH_OBSERVER(WebContentsObserver, observers_,
                     DidAttachInterstitialPage());
 }