Enable features API for content shell and webview

base/feature_list.h

 // Copyright 2015 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 BASE_FEATURE_LIST_H_
 #define BASE_FEATURE_LIST_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 127 matching lines @@
   // Returns whether the given |feature| is enabled. Must only be called after
   // the singleton instance has been registered via SetInstance(). Additionally,
   // a feature with a given name must only have a single corresponding Feature
   // struct, which is checked in builds with DCHECKs enabled.
   static bool IsEnabled(const Feature& feature);
 
   // Splits a comma-separated string containing feature names into a vector.
   static std::vector<std::string> SplitFeatureListString(
       const std::string& input);
 
-  // Initializes and sets a default instance of FeatureList if one has not yet
-  // already been set. No-op otherwise.
-  static void InitializeInstance();
+  // Initializes and sets an instance of FeatureList with feature overrides via
+  // command-line flags |enable_features| and |disable_features| if one has not
+  // already been set from command-line flags. No-op otherwise. See
+  // InitializeFromCommandLine for more details about |enable_features| and
+  // |disable_features| parameters.
+  static void InitializeInstance(const std::string& enable_features,
+                                 const std::string& disable_features);
 
   // Returns the singleton instance of FeatureList. Will return null until an
   // instance is registered via SetInstance().
   static FeatureList* GetInstance();
 
   // Registers the given |instance| to be the singleton feature list for this
   // process. This should only be called once and |instance| must not be null.
   static void SetInstance(scoped_ptr<FeatureList> instance);
 
   // Clears the previously-registered singleton instance for tests.
@@ skipping 67 matching lines @@
   // Locked map that keeps track of seen features, to ensure a single feature is
   // only defined once. This verification is only done in builds with DCHECKs
   // enabled.
   Lock feature_identity_tracker_lock_;
   std::map<std::string, const Feature*> feature_identity_tracker_;
 
   // Whether this object has been fully initialized. This gets set to true as a
   // result of FinalizeInitialization().
   bool initialized_;
 
+  // Whether this object has been initialized from command line.
+  bool initialized_from_command_line_;
+
   DISALLOW_COPY_AND_ASSIGN(FeatureList);
 };
 
 }  // namespace base
 
 #endif  // BASE_FEATURE_LIST_H_