Expand FeatureList to support FieldTrial association.

components/variations/service/variations_service.h

 // Copyright (c) 2012 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 COMPONENTS_VARIATIONS_SERVICE_VARIATIONS_SERVICE_H_
 #define COMPONENTS_VARIATIONS_SERVICE_VARIATIONS_SERVICE_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/metrics/field_trial.h"
 #include "base/observer_list.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "components/variations/service/variations_service_client.h"
 #include "components/variations/variations_request_scheduler.h"
 #include "components/variations/variations_seed_simulator.h"
 #include "components/variations/variations_seed_store.h"
 #include "components/web_resource/resource_request_allowed_notifier.h"
 #include "net/url_request/url_fetcher_delegate.h"
 #include "url/gurl.h"
 
 class PrefService;
 class PrefRegistrySimple;
 
 namespace base {
+class FeatureList;
 class Version;
 }
 
 namespace metrics {
 class MetricsStateManager;
 }
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }
@@ skipping 24 matching lines @@
     // experiment changes on a restart. This notification can then be used to
     // update UI (i.e. badging an icon).
     virtual void OnExperimentChangesDetected(Severity severity) = 0;
 
    protected:
     virtual ~Observer() {}
   };
 
   ~VariationsService() override;
 
-  // Creates field trials based on Variations Seed loaded from local prefs. If
-  // there is a problem loading the seed data, all trials specified by the seed
-  // may not be created.
-  bool CreateTrialsFromSeed();
+  // Creates field trials based on the variations seed loaded from local state.
+  // If there is a problem loading the seed data, all trials specified by the
+  // seed may not be created. Some field trials are configured to override or
+  // associate with (for reporting) specific features. These associations are
+  // registered with |feature_list|.
+  bool CreateTrialsFromSeed(base::FeatureList* feature_list);
 
   // Should be called before startup of the main message loop.
   void PerformPreMainMessageLoopStartup();
 
   // Calls FetchVariationsSeed once and repeats this periodically. See
   // implementation for details on the period. Must be called after
   // |CreateTrialsFromSeed|.
   void StartRepeatedVariationsSeedFetch();
 
   // Adds an observer to listen for detected experiment changes.
@@ skipping 202 matching lines @@
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<VariationsService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(VariationsService);
 };
 
 }  // namespace variations
 
 #endif  // COMPONENTS_VARIATIONS_SERVICE_VARIATIONS_SERVICE_H_