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)
+      continue;
+
+    std::vector<std::string> group_parts;
+    base::SplitString(experiment[0], '.', &group_parts);
+    if (group_parts.size() != 2)
+      continue;
+
+    std::vector<std::string> key_values;
+    base::SplitString(experiment[1], '/', &key_values);
+    if (key_values.size() % 2 == 0) {
+      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 21:08:10]

Indent 2 more. You can also run "git cl format" to let the tools do this for
you.

[danduong, 2015/04/29 21:28:14]

Done.

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

[Alexei Svitkine (slow), 2015/04/29 21:08:10]

You always return true. Perhaps we should return false if the param has an
invalid format and CHECK on it like we do for --force-fieldtrials=?

[danduong, 2015/04/29 21:28:14]

Done.

+}
+
 }  // namespace chrome_variations