Flip --enable-apps-show-on-first-paint flag.

apps/app_window.h

Index: apps/app_window.h
diff --git a/apps/app_window.h b/apps/app_window.h
index 1c19c0c8e77b5016c8dcef8e84c5843277ac3a9c..81a1973daf09b451472dc4bd503563b52031b515 100644
--- a/apps/app_window.h
+++ b/apps/app_window.h
@@ -69,6 +69,9 @@ class AppWindowContents {
   // Called when the native window closes.
   virtual void NativeWindowClosed() = 0;
 
+  // Called with the native window is first shown.
+  virtual void NativeWindowFirstShown() const = 0;
+
   virtual content::WebContents* GetWebContents() const = 0;
 
  private:
@@ -523,6 +526,9 @@ class AppWindow : public content::NotificationObserver,
   // The first visually non-empty paint has completed.
   bool first_paint_complete_;
 
+  // The window has been shown.
+  bool has_been_shown_;
+
   // Whether the window is hidden or not. Hidden in this context means actively
   // by the chrome.app.window API, not in an operating system context. For
   // example windows which are minimized are not hidden, and windows which are