Add support for variations controlled overriding UI strings to the variations service.

components/variations/variations_seed_processor.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 COMPONENTS_VARIATIONS_VARIATIONS_SEED_PROCESSOR_H_
 #define COMPONENTS_VARIATIONS_VARIATIONS_SEED_PROCESSOR_H_
 
 #include <string>
 #include <vector>
 
+#include "base/callback_forward.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/metrics/field_trial.h"
+#include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "base/version.h"
 #include "components/variations/proto/study.pb.h"
 #include "components/variations/proto/variations_seed.pb.h"
 
 namespace chrome_variations {
 
 class ProcessedStudy;
 
 // Helper class to instantiate field trials from a variations seed.
 class VariationsSeedProcessor {
  public:
+  typedef base::Callback<void(uint32_t,
+                              const base::string16&)> UIStringOverrideCallback;
+
   VariationsSeedProcessor();
   virtual ~VariationsSeedProcessor();
 
   // Creates field trials from the specified variations |seed|, based on the
   // specified configuration (locale, current date, version, channel, form
   // factor and hardware_class).
   void CreateTrialsFromSeed(const VariationsSeed& seed,
                             const std::string& locale,
                             const base::Time& reference_date,
                             const base::Version& version,
                             Study_Channel channel,
                             Study_FormFactor form_factor,
-                            const std::string& hardware_class);
+                            const std::string& hardware_class,
+                            const UIStringOverrideCallback& override_callback);
 
  private:
   friend class VariationsSeedProcessorTest;
   FRIEND_TEST_ALL_PREFIXES(VariationsSeedProcessorTest,
                            AllowForceGroupAndVariationId);
   FRIEND_TEST_ALL_PREFIXES(VariationsSeedProcessorTest,
                            AllowVariationIdWithForcingFlag);
   FRIEND_TEST_ALL_PREFIXES(VariationsSeedProcessorTest,
                            ForbidForceGroupWithVariationId);
   FRIEND_TEST_ALL_PREFIXES(VariationsSeedProcessorTest, ForceGroupWithFlag1);
   FRIEND_TEST_ALL_PREFIXES(VariationsSeedProcessorTest, ForceGroupWithFlag2);
   FRIEND_TEST_ALL_PREFIXES(VariationsSeedProcessorTest,
                            ForceGroup_ChooseFirstGroupWithFlag);
   FRIEND_TEST_ALL_PREFIXES(VariationsSeedProcessorTest,
                            ForceGroup_DontChooseGroupWithFlag);
   FRIEND_TEST_ALL_PREFIXES(VariationsSeedProcessorTest, IsStudyExpired);
   FRIEND_TEST_ALL_PREFIXES(VariationsSeedProcessorTest, VariationParams);
   FRIEND_TEST_ALL_PREFIXES(VariationsSeedProcessorTest,
                            VariationParamsWithForcingFlag);
 
   // Check if the |study| is only associated with platform Android/iOS and
   // channel dev/canary. If so, forcing flag and variation id can both be set.
   // (Otherwise, forcing_flag and variation_id are mutually exclusive.)
   bool AllowVariationIdWithForcingFlag(const Study& study);
 
   // Creates and registers a field trial from the |processed_study| data.
   // Disables the trial if |processed_study.is_expired| is true.
-  void CreateTrialFromStudy(const ProcessedStudy& processed_study);
+  void CreateTrialFromStudy(const ProcessedStudy& processed_study,
+                            const UIStringOverrideCallback& override_callback);
 
   DISALLOW_COPY_AND_ASSIGN(VariationsSeedProcessor);
 };
 
 }  // namespace chrome_variations
 
 #endif  // COMPONENTS_VARIATIONS_VARIATIONS_SEED_PROCESSOR_H_