Add iOS to the variations study proto.

chrome/browser/metrics/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 chrome_variations;
 
@@ skipping 58 matching lines @@
   // See: http://dev.chromium.org/getting-involved/dev-channel
   enum Channel {
     CANARY = 0;
     DEV = 1;
     BETA = 2;
     STABLE = 3;
   }
 
   // Possible Chrome operating system platforms.
   enum Platform {
-    PLATFORM_WINDOWS = 0;
-    PLATFORM_MAC = 1;
-    PLATFORM_LINUX = 2;
+    PLATFORM_WINDOWS  = 0;
+    PLATFORM_MAC      = 1;
+    PLATFORM_LINUX    = 2;
     PLATFORM_CHROMEOS = 3;
-    PLATFORM_ANDROID = 4;
+    PLATFORM_ANDROID  = 4;
+    PLATFORM_IOS      = 5;
   }
 
   // Filtering criteria specifying whether this study is applicable to a given
   // Chrome instance.
   //
   // Next tag: 6
   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
     // Ex: 1330893974  (corresponds to 2012-03-04 20:46:14Z)
@@ skipping 21 matching lines @@
     // List of platforms that will receive this study. If omitted, the study
     // applies to all platforms.
     // Ex: [PLATFORM_WINDOWS, PLATFORM_MAC]
     repeated Platform platform = 5;
   }
 
   // Filtering criteria for this study. A study that is filtered out for a given
   // client is equivalent to that study not being sent at all.
   optional Filter filter = 10;
 }