Change infobar creation to use a public static Create() method on the infobar delegate classes.

chrome/browser/api/infobars/simple_alert_infobar_delegate.h

Index: chrome/browser/api/infobars/simple_alert_infobar_delegate.h
===================================================================
--- chrome/browser/api/infobars/simple_alert_infobar_delegate.h	(revision 175396)
+++ chrome/browser/api/infobars/simple_alert_infobar_delegate.h	(working copy)
@@ -12,12 +12,17 @@
 
 class SimpleAlertInfoBarDelegate : public ConfirmInfoBarDelegate {
  public:
+  // Creates a simple alert delegate and adds it to |infobar_service|.
+  static void Create(InfoBarService* infobar_service,
+                     gfx::Image* icon,  // May be NULL.
+                     const string16& message,
+                     bool auto_expire);
+
+ private:
   SimpleAlertInfoBarDelegate(InfoBarService* infobar_service,
-                             gfx::Image* icon,  // May be NULL.
+                             gfx::Image* icon,
                              const string16& message,
                              bool auto_expire);
-
- private:
   virtual ~SimpleAlertInfoBarDelegate();
 
   // ConfirmInfoBarDelegate: