Make FeatureList override state be plumbed to renderer processes.

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 99 matching lines @@
   // feature to |override_state|. Command-line overrides still take precedence
   // over field trials, so this will have no effect if the feature is being
   // overridden from the command-line. The associated field trial will be
   // activated when the feature state for this feature is queried. This should
   // be called during registration, after InitializeFromCommandLine() has been
   // called but before the instance is registered via SetInstance().
   void RegisterFieldTrialOverride(const std::string& feature_name,
                                   OverrideState override_state,
                                   FieldTrial* field_trial);
 
+  // Returns comma-separated lists of feature names (in the same format that is
+  // accepted by InitializeFromCommandLine()) corresponding to features that
+  // have been overridden - either through command-line or via FieldTrials.
+  // Must be called only after the instance has been initialized and registered.
+  void GetFeatureOverrides(std::string* enable_overrides,
+                           std::string* disable_overrides);
+
   // 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);
 
@@ skipping 79 matching lines @@
   // Whether this object has been fully initialized. This gets set to true as a
   // result of FinalizeInitialization().
   bool initialized_;
 
   DISALLOW_COPY_AND_ASSIGN(FeatureList);
 };
 
 }  // namespace base
 
 #endif  // BASE_FEATURE_LIST_H_