Fix showing constrained window for uninitialized tabs

chrome/browser/ui/cocoa/constrained_window/constrained_window_mac2.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_UI_COCOA_CONSTRAINED_WINDOW_CONSTRAINED_WINDOW_MAC_2_
 #define CHROME_BROWSER_UI_COCOA_CONSTRAINED_WINDOW_CONSTRAINED_WINDOW_MAC_2_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/memory/scoped_nsobject.h"
 #include "chrome/browser/ui/constrained_window.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
 
 namespace content {
 class WebContents;
 }
 class ConstrainedWindowMac2;
 
 // A delegate for a constrained window. The delegate is notified when the
 // window closes.
 class ConstrainedWindowMacDelegate2 {
  public:
   virtual void OnConstrainedWindowClosed(ConstrainedWindowMac2* window) = 0;
 };
 
 // Constrained window implementation for Mac.
 // Normally an instance of this class is owned by the delegate. The delegate
 // should delete the instance when the window is closed.
-class ConstrainedWindowMac2 : public ConstrainedWindow {
+class ConstrainedWindowMac2 : public ConstrainedWindow,
+                              public content::NotificationObserver {
  public:
   ConstrainedWindowMac2(ConstrainedWindowMacDelegate2* delegate,
                         content::WebContents* web_contents,
                         NSWindow* window);
   virtual ~ConstrainedWindowMac2();
 
   // ConstrainedWindow implementation.
   virtual void ShowConstrainedWindow() OVERRIDE;
   // Closes the constrained window and deletes this instance.
   virtual void CloseConstrainedWindow() OVERRIDE;
   virtual void PulseConstrainedWindow() OVERRIDE;
   virtual gfx::NativeWindow GetNativeWindow() OVERRIDE;
   virtual bool CanShowConstrainedWindow() OVERRIDE;
 
+  // content::NotificationObserver:
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
  private:
   // Gets the parent window of the dialog.
   NSWindow* GetParentWindow() const;
 
   ConstrainedWindowMacDelegate2* delegate_;  // weak, owns us.
 
   // The WebContents that owns and constrains this ConstrainedWindow. Weak.
   content::WebContents* web_contents_;
 
   scoped_nsobject<NSWindow> window_;
+
+  // A scoped container for notification registries.
+  content::NotificationRegistrar registrar_;
+
+  // This is true if the constrained window is waiting to be shown.
+  bool pending_show_;
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_CONSTRAINED_WINDOW_CONSTRAINED_WINDOW_MAC_2_