Extract permission alias info from PermissionsProvider

extensions/common/alias_provider.cc

Index: extensions/common/alias_provider.cc
diff --git a/extensions/common/alias_provider.cc b/extensions/common/alias_provider.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d3ffc1b2eb2b78fdcb0aa58b98e2b9fd3faf9aff
--- /dev/null
+++ b/extensions/common/alias_provider.cc
@@ -0,0 +1,32 @@
+// 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_provider.h"
+
+namespace extensions {
+
+AliasProvider::AliasProvider() {}
+
+AliasProvider::~AliasProvider() {}
+
+std::vector<Alias> AliasProvider::GetValidApiAliases() const {
+  return FilterOutInvalidAliases(GetApiAliases());
+}
+
+std::vector<Alias> AliasProvider::GetValidPermissionAliases() const {
+  return FilterOutInvalidAliases(GetPermissionAliases());
+}
+
+std::vector<Alias> AliasProvider::FilterOutInvalidAliases(
+    const std::vector<Alias>& aliases) const {
+  std::vector<Alias> result;
+  for (const auto& alias : aliases) {
+    if (alias.valid()) {
+      result.push_back(alias);
+    }
+  }
+  return result;
+}
+
+}  // namespace extensions