Panels refactor: Support browserless panels on Linux.

chrome/browser/ui/panels/panel_host.h

Index: chrome/browser/ui/panels/panel_host.h
diff --git a/chrome/browser/ui/panels/panel_host.h b/chrome/browser/ui/panels/panel_host.h
index fa68c3d4cbca6fb9d5fa3ac102de372ebe117a61..f2732c27e25f36eb0ffb6256e9f5169e7a05ed11 100644
--- a/chrome/browser/ui/panels/panel_host.h
+++ b/chrome/browser/ui/panels/panel_host.h
@@ -15,6 +15,7 @@
 class FaviconTabHelper;
 class GURL;
 class Panel;
+class PrefsTabHelper;
 class Profile;
 
 namespace content {
@@ -98,6 +99,7 @@ class PanelHost : public content::WebContentsDelegate,
   // The following factory is used to close the panel via the message loop.
   base::WeakPtrFactory<PanelHost> weak_factory_;
 
+  scoped_ptr<PrefsTabHelper> prefs_tab_helper_;
   scoped_ptr<FaviconTabHelper> favicon_tab_helper_;
   scoped_ptr<content::WebContents> web_contents_;