PlzNavigate: inform the WebFrameClient that a form will be submitted

content/browser/frame_host/navigator_impl.cc

Index: content/browser/frame_host/navigator_impl.cc
diff --git a/content/browser/frame_host/navigator_impl.cc b/content/browser/frame_host/navigator_impl.cc
index 788c23d356b18b45d4df4d95cec5b5bfa4f5ae1a..410f62d2b70a1d0998a0424862defc31644f84ae 100644
--- a/content/browser/frame_host/navigator_impl.cc
+++ b/content/browser/frame_host/navigator_impl.cc
@@ -676,6 +676,8 @@ void NavigatorImpl::OnBeginNavigation(
       (ongoing_navigation_request->browser_initiated() ||
        ongoing_navigation_request->begin_params().has_user_gesture) &&
       !begin_params.has_user_gesture) {
+    // Inform the renderer that its request will not be treated.
+    frame_tree_node->current_frame_host()->Stop();
     return;
   }
 
@@ -787,6 +789,14 @@ void NavigatorImpl::FailedNavigation(FrameTreeNode* frame_tree_node,
 void NavigatorImpl::CancelNavigation(FrameTreeNode* frame_tree_node) {
   CHECK(base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableBrowserSideNavigation));
+  NavigationRequest* navigation_request = frame_tree_node->navigation_request();
+
+  // If the navigation was renderer-initiated, the renderer expects the browser
+  // to be treating it. Inform the renderer that the navigation is no longer
+  // ongoing.
+  if (navigation_request && !navigation_request->browser_initiated())
+    frame_tree_node->current_frame_host()->Stop();
+
   frame_tree_node->ResetNavigationRequest(false);
   if (frame_tree_node->IsMainFrame())
     navigation_data_.reset();