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

components/variations/variations_associated_data.cc

Index: components/variations/variations_associated_data.cc
diff --git a/components/variations/variations_associated_data.cc b/components/variations/variations_associated_data.cc
index a26470438fb2cc3fd69acd89a336e9c5c33d750f..684dc93fd5d3da4d8cf6f354b7eac113e8d723ba 100644
--- a/components/variations/variations_associated_data.cc
+++ b/components/variations/variations_associated_data.cc
@@ -9,6 +9,7 @@
 #include <vector>
 
 #include "base/memory/singleton.h"
+#include "base/strings/string_split.h"
 
 namespace variations {
 
@@ -215,6 +216,53 @@ bool AssociateVariationParams(
       trial_name, group_name, params);
 }
 
+struct VarationsParams {
+  std::string GroupName;
+  std::map<std::string, std::string> Params;
+};
+
+bool AssociateParamsFromString(const std::string& varations_string) {
+  std::map <std::string, VarationsParams> data;
+  std::vector<std::string> tokens;
+  base::SplitString(varations_string, '/', &tokens);
+  if (tokens.size() % 2 == 0) {
+    // Build out parameters
+    for (int i = 0; i < tokens.size(); i += 2) {
+      std::vector<std::string> key;
+      base::SplitString(tokens[i], '.', &key);
+      DCHECK(key.size() == 3) << "Expecting format Trial.Group.Key";
+      if (key.size() == 3) {
+        const std::string& trial = key[0];
+        const std::string& group = key[1];
+        const std::string& param = key[2];
+        const std::string& value = tokens[i + 1];
+        const auto& iter = data.find(trial);
+        if (iter != data.end()) {
+          if (iter->second.GroupName == group) {
+            iter->second.Params[param] = value;
+          }
+        }
+        else {
+          VarationsParams vp;
+          vp.GroupName = group;
+          vp.Params[param] = value;
+          data[trial] = vp;
+        }
+      }
+    }
+    // Associate parameters
+    for (const auto& iter : data) {
+      const std::string& trial = iter.first;
+      const VarationsParams& params = iter.second;
+      AssociateVariationParams(trial, params.GroupName, params.Params);
+    }
+  } else {
+    DCHECK(false) << "Expecting pairs of values";
+    return false;
+  }
+  return true;
+}
+
 bool GetVariationParams(const std::string& trial_name,
                         std::map<std::string, std::string>* params) {
   return VariationsParamAssociator::GetInstance()->GetVariationParams(