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

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 chrome_variations;
 
@@ skipping 25 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: 9
+  // Next tag: 10
   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 43 matching lines @@
       KILL_BEST_EFFORT = 2;
 
       // This is a kill-switch group that should be killed with "critical"
       // priority. Depending on platform this may result in showing a
       // non-dismissible restart prompt with a timer. This should only be used
       // in very serious emergency circumstances. The experiment must have a
       // probability_weight of 0.
       KILL_CRITICAL = 3;
     }
     optional Type type = 7 [default = NORMAL];
+
+    // A UI string to override, and the new value to use. |name_hash| is the
+    // hash of the resource name to be overridden.

[Alexei Svitkine (slow), 2014/07/17 13:43:31]

Nit: The second sentence is redundant given there's a comment below about
|name_hash| - either incorporate it int the comment below or just remove
altogether.

[jwd, 2014/07/18 20:10:29]

Done.

+    message OverrideUIString {
+      // The first 32 bits of the MD5 hash digest of the resource name to
+      // override.
+      // e.g. Hash("IDS_BOOKMARK_BAR_UNDO")
+      optional fixed32 name_hash = 1;
+      // The new value of the string being overridden.

[Alexei Svitkine (slow), 2014/07/17 13:43:31]

Add an empty line above this.

[jwd, 2014/07/18 20:10:29]

Done.

+      // e.g. "Undo"
+      optional string value = 2;
+    }
+    repeated OverrideUIString override_ui_string = 9;
   }
 
   // List of experiments in this study. This list should include the default /
   // control experiment.
   //
   // For example, to specify that 99% of users get the default behavior, while
   // 0.5% of users get experience "A" and 0.5% of users get experience "B",
   // specify the values below.
   // Ex: { "default": 990, "A": 5, "B": 5 }
   repeated Experiment experiment = 9;
@@ skipping 103 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;
 }