Expand FeatureList to support FieldTrial association.

components/variations/proto/study.proto

 // 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.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package variations;
 
@@ skipping 26 matching lines @@
   // Ex: PERMANENT
   optional Consistency consistency = 7 [default = SESSION];
 
   // Name of the experiment that gets the default experience. This experiment
   // must be included in the list below.
   // Ex: "default"
   optional string default_experiment_name = 8;
 
   // An experiment within the study.
   //
-  // Next tag: 11
+  // Next tag: 12
   message Experiment {
     // A named parameter value for this experiment.
     //
     // Next tag: 3
     message Param {
       // The name of the parameter.
       optional string name = 1;
 
       // The value of the parameter.
       optional string value = 2;
@@ skipping 14 matching lines @@
     // Optional id used to allow this experiment to trigger experimental
     // behavior on Google web properties.
     optional uint64 google_web_trigger_experiment_id = 8;
 
     // Optional id used to uniquely identify this experiment for Google Update.
     optional uint64 google_update_experiment_id = 4;
 
     // Optional id used to uniquely identify this experiment for Chrome Sync.
     optional uint64 chrome_sync_experiment_id = 10;
 
+    // Specifies the feature association parameters for this experiment group.
+    //
+    // Next tag: 5
+    message FeatureAssociation {
+      // Optional list of features to enable when this experiment is selected.

[rkaplow, 2015/09/14 21:20:12]

can you mention here the relative priorities of enable/disable

[Alexei Svitkine (slow), 2015/09/14 22:03:44]

Instead, I expanded the comments to disallow the case where a feature appears in
both lists. Also mention that this does not take precedence over command-line
overrides.

+      repeated string enable_feature = 1;
+
+      // Optional list of features to disable when this experiment is selected.
+      repeated string disable_feature = 2;
+
+      // Similar to |forcing_flag|, this is an optional name of a feature which
+      // will cause this experiment to be forced on, if that feature is enabled
+      // from the command-line. Experiment with this set are not eligible for
+      // selection via a random dice roll.
+      optional string forcing_feature_on = 3;
+
+      // Similar to |forcing_flag|, this is an optional name of a feature which
+      // will cause this experiment to be forced on, if that feature is disabled

[rkaplow, 2015/09/14 21:20:12]

this is meant to be off, right? 

[Alexei Svitkine (slow), 2015/09/14 22:03:43]

Done.

+      // from the command-line. Experiment with this set are not eligible for
+      // selection via a random dice roll.
+      optional string forcing_feature_off = 4;
+    }
+    optional FeatureAssociation feature_association = 11;
+
     // Optional name of a Chrome flag that, when present, causes this experiment
     // to be forced. If the forcing_flag field is set, users will not be
     // assigned to this experiment unless that flag is present in Chrome's
     // command line.
     optional string forcing_flag = 5;
 
     // Parameter values for this experiment.
     repeated Param param = 6;
 
     enum Type {
@@ skipping 161 matching lines @@
     // This is recommended for most studies that include client code.
     ACTIVATION_EXPLICIT  = 0;
     // The study will be automatically activated when it is created. This
     // is recommended for studies that do not have any client logic.
     ACTIVATION_AUTO      = 1;
   }
 
   // Activation type for this study. Defaults to ACTIVATION_EXPLICIT if omitted.
   optional ActivationType activation_type = 12;
 }