Fix showing constrained window for uninitialized tabs

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

Index: chrome/browser/ui/cocoa/constrained_window/constrained_window_mac2.h
diff --git a/chrome/browser/ui/cocoa/constrained_window/constrained_window_mac2.h b/chrome/browser/ui/cocoa/constrained_window/constrained_window_mac2.h
index 24ef877772166c2c7666d205a69f63c2a4848c79..8704135e14ebc09551632f3f3e464a9db2c57bd2 100644
--- a/chrome/browser/ui/cocoa/constrained_window/constrained_window_mac2.h
+++ b/chrome/browser/ui/cocoa/constrained_window/constrained_window_mac2.h
@@ -9,6 +9,8 @@
 
 #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;
@@ -25,7 +27,8 @@ class ConstrainedWindowMacDelegate2 {
 // 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,
@@ -40,6 +43,11 @@ class ConstrainedWindowMac2 : public ConstrainedWindow {
   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;
@@ -50,6 +58,12 @@ class ConstrainedWindowMac2 : public ConstrainedWindow {
   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_