Comment FormFactor enum in study proto

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 174 matching lines @@
     PLATFORM_WINDOWS  = 0;
     PLATFORM_MAC      = 1;
     PLATFORM_LINUX    = 2;
     PLATFORM_CHROMEOS = 3;
     PLATFORM_ANDROID  = 4;
     PLATFORM_IOS      = 5;
   }
 
   // Possible form factors Chrome is running on.
   enum FormFactor {
+    // Chrome Desktop on Windows, Mac, Linux, or ChromeOS.
     DESKTOP = 0;
+    // Phone-based mobile Chrome, e.g. an Android phone or iPhone.
     PHONE   = 1;
+    // Tablet-based mobile Chrome, e.g. an Android tablet or iPad.
     TABLET  = 2;
+    // ChromeOS running in single-app Kiosk mode.
     KIOSK   = 3;
   }
 
   // Filtering criteria specifying whether this study is applicable to a given
   // Chrome instance.
   //
   // Next tag: 15
   message Filter {
     // The start date of the study in Unix time format. (Seconds since midnight
     // January 1, 1970 UTC). See: http://en.wikipedia.org/wiki/Unix_time
@@ skipping 104 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;
 }