Add support for app_shell-only extension APIs

extensions/shell/browser/api/shell_identity/shell_identity_api.cc

Index: extensions/shell/browser/api/shell_identity/shell_identity_api.cc
diff --git a/extensions/shell/browser/api/shell_identity/shell_identity_api.cc b/extensions/shell/browser/api/shell_identity/shell_identity_api.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7118fac9f17531e66a076946315131efa8cd94b5
--- /dev/null
+++ b/extensions/shell/browser/api/shell_identity/shell_identity_api.cc
@@ -0,0 +1,23 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "extensions/shell/browser/api/shell_identity/shell_identity_api.h"
+
+#include "base/logging.h"
+
+namespace extensions {
+
+ShellIdentityGetAuthTokenFunction::ShellIdentityGetAuthTokenFunction() {
+}
+
+ShellIdentityGetAuthTokenFunction::~ShellIdentityGetAuthTokenFunction() {
+}
+
+ExtensionFunction::ResponseAction ShellIdentityGetAuthTokenFunction::Run() {
+  // TODO(jamescook): Implement this.
+  NOTIMPLEMENTED();
+  return RespondNow(NoArguments());
+}
+
+}  // namespace extensions