Add support for command line switches to Features, and as proof that it works,

extensions/common/features/feature.h

 // Copyright 2013 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_FEATURE_H_
 #define EXTENSIONS_COMMON_FEATURES_FEATURE_H_
 
 #include <set>
 #include <string>
 
@@ skipping 55 matching lines @@
     INVALID_URL,
     INVALID_TYPE,
     INVALID_CONTEXT,
     INVALID_LOCATION,
     INVALID_PLATFORM,
     INVALID_MIN_MANIFEST_VERSION,
     INVALID_MAX_MANIFEST_VERSION,
     NOT_PRESENT,
     UNSUPPORTED_CHANNEL,
     FOUND_IN_BLACKLIST,
+    MISSING_COMMAND_LINE_SWITCH,
   };
 
   // Container for AvailabiltyResult that also exposes a user-visible error
   // message in cases where the feature is not available.
   class Availability {
    public:
     AvailabilityResult result() const { return result_; }
     bool is_available() const { return result_ == IS_AVAILABLE; }
     const std::string& message() const { return message_; }
 
@@ skipping 56 matching lines @@
   virtual Availability IsAvailableToContext(const Extension* extension,
                                             Context context,
                                             const GURL& url,
                                             Platform platform) const = 0;
 
   virtual std::string GetAvailabilityMessage(AvailabilityResult result,
                                              Manifest::Type type,
                                              const GURL& url,
                                              Context context) const = 0;
 
+  // Returns true if the feature is available to the current environment,
+  // without needing to know information about an Extension or any other
+  // contextual information. Typically used when the Feature is purely
+  // configured by command line flags and/or Chrome channel.
+  //
+  // Generally try not to use this function. Even if you don't think a Feature
+  // relies on an Extension now - maybe it will, one day, so if there's an
+  // Extension available (or a runtime context, etc) then use the more targeted
+  // method instead.
+  Availability IsAvailableToEnvironment() const;
+
   virtual bool IsIdInBlacklist(const std::string& extension_id) const = 0;
   virtual bool IsIdInWhitelist(const std::string& extension_id) const = 0;
 
  protected:
   std::string name_;
   bool no_parent_;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_FEATURES_FEATURE_H_