Add a mechanism to force parameters of a group to a specific value.

chrome/common/variations/variations_util.cc

 // Copyright 2014 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.
 
 #include "chrome/common/variations/variations_util.h"
 
 #include <string>
 #include <vector>
 
+#include "base/strings/string_split.h"
 #include "chrome/common/child_process_logging.h"
 #include "chrome/common/crash_keys.h"
 #include "components/variations/active_field_trials.h"
+#include "components/variations/variations_associated_data.h"
+#include "net/base/escape.h"
 
 namespace chrome_variations {
 
 void SetChildProcessLoggingVariationList() {
   std::vector<std::string> experiment_strings;
   variations::GetFieldTrialActiveGroupIdsAsStrings(&experiment_strings);
   crash_keys::SetVariationsList(experiment_strings);
 }
 
+bool AssociateParamsFromString(const std::string& varations_string) {
+  // Format: Trial1.Group1:k1/v1/k2/v2,Trial2.Group2:k1/v1/k2/v2
+  std::vector<std::string> experiment_groups;
+  base::SplitString(varations_string, ',', &experiment_groups);
+  for (const auto& experiment_group : experiment_groups) {
+    std::vector<std::string> experiment;
+    base::SplitString(experiment_group, ':', &experiment);
+    if (experiment.size() != 2)
+      return false;
+
+    std::vector<std::string> group_parts;
+    base::SplitString(experiment[0], '.', &group_parts);
+    if (group_parts.size() != 2)
+      return false;
+
+    std::vector<std::string> key_values;
+    base::SplitString(experiment[1], '/', &key_values);
+    if (key_values.size() % 2 != 0)
+      return false;
+
+    std::map<std::string, std::string> params;
+    for (int i = 0; i < key_values.size(); i += 2) {
+      std::string key = net::UnescapeURLComponent(
+          key_values[i], net::UnescapeRule::URL_SPECIAL_CHARS);
+      std::string value = net::UnescapeURLComponent(
+          key_values[i + 1], net::UnescapeRule::URL_SPECIAL_CHARS);
+      params[key] = value;
+    }
+    std::string trial = net::UnescapeURLComponent(
+        group_parts[0], net::UnescapeRule::URL_SPECIAL_CHARS);

[Alexei Svitkine (slow), 2015/04/29 22:02:39]

Nit: I think if you make a helper wrapping this net:: call the rest of the code
can be much more concise.

[danduong, 2015/04/29 22:17:49]

Done.

+    std::string group = net::UnescapeURLComponent(
+        group_parts[1], net::UnescapeRule::URL_SPECIAL_CHARS);
+    variations::AssociateVariationParams(trial, group, params);
+  }
+  return true;
+}
+
 }  // namespace chrome_variations