Extract permission alias info from PermissionsProvider

extensions/common/alias.h

Index: extensions/common/alias.h
diff --git a/extensions/common/alias.h b/extensions/common/alias.h
new file mode 100644
index 0000000000000000000000000000000000000000..03299b32a55259ab9a402bfbd551b1a02a35b822
--- /dev/null
+++ b/extensions/common/alias.h
@@ -0,0 +1,40 @@
+// Copyright 2016 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_COMMON_ALIAS_H_
+#define EXTENSIONS_COMMON_ALIAS_H_
+
+#include <string>
+
+namespace extensions {
+
+// Information about an alias.
+// Main usage: describing aliases for extension features (extension permissions,
+// APIs), which is useful for ensuring backward-compatibility of extension
+// features when they get renamed. Old feature name can be defined as an alias
+// for the new feature name - this would ensure that the extensions using the
+// old feature name don't break.
+class Alias {
+ public:
+  // |name|: The alias name.
+  // |real_name|: The real name behind alias.
+  Alias(const char* const name, const char* const real_name)
+      : name_(name), real_name_(real_name) {}
+  ~Alias() {}
+
+  const std::string& name() const { return name_; }
+
+  const std::string& real_name() const { return real_name_; }
+
+ private:
+  // The alias name.
+  std::string name_;
+
+  // The real name behind the alias.
+  std::string real_name_;
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_COMMON_ALIAS_H_