Cache --whitelisted-extension-id in SimpleFeature.

extensions/common/features/simple_feature.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_COMMON_FEATURES_SIMPLE_FEATURE_H_
 #define EXTENSIONS_COMMON_FEATURES_SIMPLE_FEATURE_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 121 matching lines @@
                                   const GURL& url) const;
   Availability CreateAvailability(AvailabilityResult result,
                                   Context context) const;
 
  private:
   bool MatchesManifestLocation(Manifest::Location manifest_location) const;
 
   Availability CheckDependencies(
       const base::Callback<Availability(const Feature*)>& checker) const;
 
+  // A singleton copy of the --whitelisted-extension-id so that we don't need to
+  // copy it from the CommandLine each time.
+  static const std::string& whitelisted_extension_id();
+
   // For clarity and consistency, we handle the default value of each of these
   // members the same way: it matches everything. It is up to the higher level
   // code that reads Features out of static data to validate that data and set
   // sensible defaults.
   std::set<std::string> blacklist_;
   std::set<std::string> whitelist_;
   std::set<std::string> dependencies_;
   std::set<Manifest::Type> extension_types_;
   std::set<Context> contexts_;
   URLPatternSet matches_;
   Location location_;
   std::set<Platform> platforms_;
   int min_manifest_version_;
   int max_manifest_version_;
   bool component_extensions_auto_granted_;
   std::string command_line_switch_;
 
   ScopedVector<SimpleFeatureFilter> filters_;;
 
   DISALLOW_COPY_AND_ASSIGN(SimpleFeature);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_FEATURES_SIMPLE_FEATURE_H_