PlzNavigate: fix timing issue in app window creation

extensions/browser/app_window/app_window.h

Index: extensions/browser/app_window/app_window.h
diff --git a/extensions/browser/app_window/app_window.h b/extensions/browser/app_window/app_window.h
index 4a06269bd05b5f04cba88e6d67d26d40586e0e82..2fe06687dfa1760bef44173d692f46b15613452c 100644
--- a/extensions/browser/app_window/app_window.h
+++ b/extensions/browser/app_window/app_window.h
@@ -242,6 +242,13 @@ class AppWindow : public content::WebContentsDelegate,
   // is on startup and from within UpdateWindowTitle().
   base::string16 GetTitle() const;
 
+  // |callback| will then be called when the first navigation in the window is
+  // ready to commit.
+  void SetOnFirstCommitCallback(const base::Closure& callback);
+
+  // Called when the first navigation in the window is ready to commit.
+  void OnReadyToCommitFirstNavigation();
+
   // Call to notify ShellRegistry and delete the window. Subclasses should
   // invoke this method instead of using "delete this".
   void OnNativeClose();
@@ -555,6 +562,9 @@ class AppWindow : public content::WebContentsDelegate,
   // Whether |is_ime_window| was set in the CreateParams.
   bool is_ime_window_;
 
+  // PlzNavigate: this is called when the first navigation is ready to commit.
+  base::Closure on_first_commit_callback_;
+
   base::WeakPtrFactory<AppWindow> image_loader_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AppWindow);