PlzNavigate: fix timing issue in app window creation

extensions/browser/api/app_window/app_window_api.cc

Index: extensions/browser/api/app_window/app_window_api.cc
diff --git a/extensions/browser/api/app_window/app_window_api.cc b/extensions/browser/api/app_window/app_window_api.cc
index 2cd0710b7f5d05df23e8d0eeea88f9c3d0f538a1..71241923ec8527fe51d6b8d02f165129f9b0eebb 100644
--- a/extensions/browser/api/app_window/app_window_api.cc
+++ b/extensions/browser/api/app_window/app_window_api.cc
@@ -14,6 +14,7 @@
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/common/content_switches.h"
 #include "content/public/common/url_constants.h"
 #include "extensions/browser/app_window/app_window.h"
 #include "extensions/browser/app_window/app_window_client.h"
@@ -367,6 +368,16 @@ bool AppWindowCreateFunction::RunAsync() {
     return true;
   }
 
+  // PlzNavigate: delay sending the response until the newly created window has
+  // been told to navigate, and blink has been correctly initialized in the
+  // renderer.
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          ::switches::kEnableBrowserSideNavigation)) {
+    app_window->SetOnFirstCommitCallback(
+        base::Bind(&AppWindowCreateFunction::SendResponse, this, true));
+    return true;
+  }
+
   SendResponse(true);
   app_window->WindowEventsReady();