Use Study and Experiment Terminology on the C++ Side For Fieldtrials

chrome/common/variations/fieldtrial_testing_config_schema.json

 // 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.
 
 {
   "type_name": "FieldTrialTestingConfig",
   "schema": [{
-    "field": "trials",
+    "field": "studies",
     "type": "array",
     "contents": {
-      "type_name": "FieldTrialTestingTrial",
+      "type_name": "FieldTrialTestingStudy",
       "type": "struct",
       "fields": [
         {"field": "name", "type": "string"},
         {
-          "field": "groups",
+          "field": "experiments",
           "type": "array",
           "contents": {
-            "type_name": "FieldTrialTestingGroup",
+            "type_name": "FieldTrialTestingExperiment",
             "type": "struct",
             "fields": [
               {"field": "name", "type": "string"},
               {
                 "field": "params",
                 "type": "array",
                 "contents": {
-                  "type_name": "FieldTrialTestingGroupParams",
+                  "type_name": "FieldTrialTestingExperimentParams",
                   "type": "struct",
                   "fields": [
                     {"field": "key", "type": "string"},
                     {"field": "value", "type": "string"}
                   ]
                 }
               },
               {
                 "field": "enable_features",
                 "type": "array",
                 "contents": { "type": "string"}
               },
               {
                 "field": "disable_features",
                 "type": "array",
                 "contents": { "type": "string"}
               }
             ]
           }
         }
       ]
     }
   }]
 }