Extract permission alias info from PermissionsProvider

extensions/common/alias.cc

Index: extensions/common/alias.cc
diff --git a/extensions/common/alias.cc b/extensions/common/alias.cc
new file mode 100644
index 0000000000000000000000000000000000000000..34c4ca78ff5863bb54f8efe2e7c385474786caa2
--- /dev/null
+++ b/extensions/common/alias.cc
@@ -0,0 +1,36 @@
+// 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.
+
+#include "extensions/common/alias.h"
+
+#include "base/logging.h"
+#include "base/version.h"
+#include "components/version_info/version_info.h"
+
+namespace extensions {
+
+namespace {
+
+bool CurrentVersionWithinAliasVersionBound(const char* version_string) {
+  if (!version_string)
+    return true;
+  base::Version upper_version_bound(version_string);
+  CHECK(upper_version_bound.IsValid());
+
+  base::Version current_version(version_info::GetVersionNumber());
+  return upper_version_bound.CompareTo(current_version) > 0;
+}
+
+}  // namespace
+
+Alias::Alias(const char* const name,
+             const char* const real_name,
+             const char* const upper_version_bound)
+    : name_(name),
+      real_name_(real_name),
+      valid_(CurrentVersionWithinAliasVersionBound(upper_version_bound)) {}
+
+Alias::~Alias() {}
+
+}  // namespace extension