Create stub jingle library for iOS.

jingle/notifier/base/gaia_constants.cc

Index: jingle/notifier/base/gaia_constants.cc
diff --git a/jingle/notifier/listener/push_client_observer.cc b/jingle/notifier/base/gaia_constants.cc
similarity index 50%
copy from jingle/notifier/listener/push_client_observer.cc
copy to jingle/notifier/base/gaia_constants.cc
index 04a877b52c78ec897a02a97d3281007731bd965b..73e4d11ae87f718d9492588f0bf485375c0de9ea 100644
--- a/jingle/notifier/listener/push_client_observer.cc
+++ b/jingle/notifier/base/gaia_constants.cc
@@ -2,10 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "jingle/notifier/listener/push_client_observer.h"
+#include "jingle/notifier/base/gaia_constants.h"
 
 namespace notifier {
 
-PushClientObserver::~PushClientObserver() {}
+namespace gaia_constants {
+
+// By default use a Google cookie auth mechanism.
+const char kDefaultAuthMechanism[] = "X-GOOGLE-TOKEN";
+
+}  // namespace gaia_constants
 
 }  // namespace notifier