Add support for app_shell-only extension APIs

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

+// 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.
+
+#ifndef EXTENSIONS_SHELL_BROWSER_API_SHELL_IDENTITY_SHELL_IDENTITY_API_H_
+#define EXTENSIONS_SHELL_BROWSER_API_SHELL_IDENTITY_SHELL_IDENTITY_API_H_
+
+#include "base/macros.h"
+#include "extensions/browser/extension_function.h"
+
+namespace extensions {
+
+// TODO(jamescook): Implement this function.
+class ShellIdentityGetAuthTokenFunction : public UIThreadExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("shell.identity.getAuthToken", UNKNOWN);
+
+  ShellIdentityGetAuthTokenFunction();
+
+ protected:
+  virtual ~ShellIdentityGetAuthTokenFunction();
+
+  // ExtensionFunction:
+  virtual ResponseAction Run() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ShellIdentityGetAuthTokenFunction);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_SHELL_BROWSER_API_SHELL_IDENTITY_SHELL_IDENTITY_API_H_