Refactor GuestView construction

chrome/browser/guest_view/web_view/web_view_guest.h

Index: chrome/browser/guest_view/web_view/web_view_guest.h
diff --git a/chrome/browser/guest_view/web_view/web_view_guest.h b/chrome/browser/guest_view/web_view/web_view_guest.h
index 5b7d0456813f1b2702a22edc48aef25f07cddee9..0150bbf46b81b0ed61a47686b70e90655f47080e 100644
--- a/chrome/browser/guest_view/web_view/web_view_guest.h
+++ b/chrome/browser/guest_view/web_view/web_view_guest.h
@@ -45,8 +45,8 @@ class SimpleMenuModel;
 class WebViewGuest : public GuestView<WebViewGuest>,
                      public content::NotificationObserver {
  public:
-  WebViewGuest(content::BrowserContext* browser_context,
-               int guest_instance_id);
+  static GuestViewBase* Create(content::BrowserContext* browser_context,
+                               int guest_instance_id);
 
   // For WebViewGuest, we create special guest processes, which host the
   // tag content separately from the main application that embeds the tag.
@@ -238,6 +238,9 @@ class WebViewGuest : public GuestView<WebViewGuest>,
 
  private:
   friend class WebViewPermissionHelper;
+  WebViewGuest(content::BrowserContext* browser_context,
+               int guest_instance_id);
+
   virtual ~WebViewGuest();
 
   // Returns the top level items (ignoring submenus) as Value.