Revert of Remove the is_loading_ field from WebContentsImpl

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 1deec21173d6c6358a6a0b31b8ec4d51a9468a2a..24747fa62702e21ae156376c8b61607717c1e7c6 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -4715,13 +4715,11 @@
                    std::move(stream_override));
 }
 
-// PlzNavigate
 void RenderFrameImpl::OnFailedNavigation(
     const CommonNavigationParams& common_params,
     const RequestNavigationParams& request_params,
     bool has_stale_copy_in_cache,
     int error_code) {
-  DCHECK(IsBrowserSideNavigationEnabled());
   bool is_reload = IsReload(common_params.navigation_type);
   bool is_history_navigation = request_params.page_state.IsValid();
   WebURLRequest::CachePolicy cache_policy =
@@ -4747,9 +4745,10 @@
       frame_->isViewSourceModeEnabled());
   SendFailedProvisionalLoad(failed_request, error, frame_);
 
-  // This check should have been done on the browser side already.
   if (!ShouldDisplayErrorPageForFailedLoad(error_code, common_params.url)) {
-    NOTREACHED();
+    // TODO(avi): Remove this; we shouldn't ever be dropping navigations.
+    // http://crbug.com/501960
+    Send(new FrameHostMsg_DidDropNavigation(routing_id_));
     return;
   }
 
@@ -5527,11 +5526,6 @@
                                       item_for_history_navigation,
                                       history_load_type, is_client_redirect);
     }
-  } else {
-    // The browser expects the frame to be loading this navigation. Inform it
-    // that the load stopped if needed.
-    if (!frame_->isLoading())
-      Send(new FrameHostMsg_DidStopLoading(routing_id_));
   }
 
   // In case LoadRequest failed before didCreateDataSource was called.