Fix broken copy-paste operations on Interstitial pages.

content/browser/frame_host/interstitial_page_impl.cc

Index: content/browser/frame_host/interstitial_page_impl.cc
diff --git a/content/browser/frame_host/interstitial_page_impl.cc b/content/browser/frame_host/interstitial_page_impl.cc
index 12676d477ca215ac6e25ebd6b562dcdf5227139a..1a04a52b11a5ee010ca25244f3944f36d98a8510 100644
--- a/content/browser/frame_host/interstitial_page_impl.cc
+++ b/content/browser/frame_host/interstitial_page_impl.cc
@@ -747,6 +747,11 @@ void InterstitialPageImpl::CreateNewWindow(
   NOTREACHED() << "InterstitialPage does not support showing popups.";
 }
 
+void InterstitialPageImpl::SetFocusedFrame(FrameTreeNode* node,
+                                           SiteInstance* source) {
+  frame_tree_.SetFocusedFrame(node, source);
+}
+
 void InterstitialPageImpl::CreateNewWidget(int32_t render_process_id,
                                            int32_t route_id,
                                            blink::WebPopupType popup_type) {