Make PopupMenuTest wait for RenderWidgetHostView initialization

content/browser/site_per_process_browsertest.cc

Index: content/browser/site_per_process_browsertest.cc
diff --git a/content/browser/site_per_process_browsertest.cc b/content/browser/site_per_process_browsertest.cc
index 0812caa0472b7d754761ddbed6dfa850105691ec..cbbedc1f236c4f363a491d98a54dfa6a9034e835 100644
--- a/content/browser/site_per_process_browsertest.cc
+++ b/content/browser/site_per_process_browsertest.cc
@@ -6475,9 +6475,20 @@ IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest, PopupMenuTest) {
 
   filter->Wait();
 
-  RenderWidgetHostView* popup_view =
+  RenderWidgetHostViewAura* popup_view = static_cast<RenderWidgetHostViewAura*>(
       RenderWidgetHost::FromID(process_id, filter->last_routing_id())
-          ->GetView();
+          ->GetView());
+  // The IO thread posts to ViewMsg_ShowWidget handlers in both the message
+  // filter above and the WebContents, which initializes the popup's view.
+  // It is possible for this code to execute before the WebContents handler,
+  // in which case OnMouseEvent would be called on an uninitialized RWHVA.
+  // This loop ensures that the initialization completes before proceeding.
+  while (!popup_view->window()) {
+    base::RunLoop loop;
+    base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
+                                                  loop.QuitClosure());
+    loop.Run();
+  }
 
   RenderWidgetHostMouseEventMonitor popup_monitor(
       popup_view->GetRenderWidgetHost());
@@ -6489,8 +6500,7 @@ IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest, PopupMenuTest) {
                                 gfx::Point(10, 5), ui::EventTimeForNow(),
                                 ui::EF_LEFT_MOUSE_BUTTON,
                                 ui::EF_LEFT_MOUSE_BUTTON);
-  static_cast<RenderWidgetHostViewAura*>(popup_view)
-      ->OnMouseEvent(&mouse_up_event);
+  popup_view->OnMouseEvent(&mouse_up_event);
 
   // This verifies that the popup actually received the event, and it wasn't
   // diverted to a different RenderWidgetHostView due to mouse capture.