Refactor GuestView construction

chrome/browser/guest_view/guest_view_base.h

Index: chrome/browser/guest_view/guest_view_base.h
diff --git a/chrome/browser/guest_view/guest_view_base.h b/chrome/browser/guest_view/guest_view_base.h
index ff7ac3096612140b50fd4a37352df6964e863f2f..d8ee1a0a6facf40d6c494b60611b37e09b74af23 100644
--- a/chrome/browser/guest_view/guest_view_base.h
+++ b/chrome/browser/guest_view/guest_view_base.h
@@ -52,6 +52,13 @@ class GuestViewBase : public content::BrowserPluginGuestDelegate,
     return NULL;
   }
 
+  static void RegisterGuestViewTypes();
+
+  typedef base::Callback<GuestViewBase*(
+      content::BrowserContext*, int)> GuestCreationCallback;
+  static void RegisterGuestViewType(const std::string& view_type,
+                                    const GuestCreationCallback& callback);
+
   static GuestViewBase* Create(content::BrowserContext* browser_context,
                                int guest_instance_id,
                                const std::string& view_type);