Restoring the chrome variatioons client, with a fix for browser_test failures caused by it.

chrome/browser/metrics/proto/study.proto

Index: chrome/browser/metrics/proto/study.proto
diff --git a/chrome/browser/metrics/proto/study.proto b/chrome/browser/metrics/proto/study.proto
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+// 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;
+
+// This defines the Protocol Buffer representation of a Chrome Variations study
+// as sent to clients of the Variations server.
+//
+// Next tag: 10
+message Study {
+  // The name of the study. Should not contain spaces or special characters.
+  // Ex: "my_study"
+  required string name = 1;
+
+  // 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)
+  optional int64 start_date = 2;
+
+  // The expiry 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)
+  optional int64 expiry_date = 3;
+
+  // The minimum Chrome version for this study, allowing a trailing '*'
+  // character for pattern matching. Inclusive. (To check for a match, iterate
+  // over each component checking >= until a * or end of string is reached.)
+  // Optional - if not specified, there is no minimum version.
+  // Ex: "17.0.963.46", "17.0.963.*", "17.*"
+  optional string min_version = 4;
+
+  // The maximum Chrome version for this study; same formatting as |min_version|
+  // above. Inclusive. (To check for a match, iterate over each component
+  // checking <= until a * or end of string is reached.)
+  // Optional - if not specified, there is no maximum version.
+  // Ex: "19.*"
+  optional string max_version = 5;
+
+  // Possible Chrome release channels.
+  // See: http://dev.chromium.org/getting-involved/dev-channel
+  enum Channel {
+    CANARY = 0;
+    DEV = 1;
+    BETA = 2;
+    STABLE = 3;
+  }
+
+  // List of channels that will receive this study. If omitted, the study
+  // applies to all channels.
+  // Ex: [BETA, STABLE]
+  repeated Channel channel = 6;
+
+  // Consistency setting for a study.
+  enum Consistency {
+    SESSION = 0;  // Can't change within a session.
+    PERMANENT = 1;  // Can't change for a given user.
+  }
+
+  // Consistency setting for this study. Optional - defaults to SESSION.
+  // 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: 4
+  message Experiment {
+    // The name of the experiment within the study.
+    // Ex: "bucketA"
+    required string name = 1;
+    // The cut of the total probability taken for this group (the x in x / N,
+    // where N is the sum of all x’s).
+    // Ex: "50"
+    required uint32 probability_weight = 2;
+    // Optional id used to uniquely identify this experiment.
+    optional uint64 experiment_id = 3;
+  }
+
+  // List of experiments in this study. This list should include the default /
+  // control group.
+  //
+  // 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;
+}