Add and implement API to associate Google experiment IDs with FieldTrials.

base/metrics/field_trial.cc

Index: base/metrics/field_trial.cc
diff --git a/base/metrics/field_trial.cc b/base/metrics/field_trial.cc
index 28886f00ee7ea1ca42c2eebd23a2399ad55a0a22..17ef98cb5b070212a26faae5c2c68bff4de428e6 100644
--- a/base/metrics/field_trial.cc
+++ b/base/metrics/field_trial.cc
@@ -167,6 +167,16 @@ std::string FieldTrial::MakeName(const std::string& name_prefix,
 }
 
 // static
+FieldTrial::NameGroupId FieldTrial::MakeNameGroupId(
+    const std::string& trial_name,
+    const std::string& group_name) {
+  NameGroupId id;
+  id.name = HashName(trial_name);
+  id.group = HashName(group_name);
+  return id;
+}
+
+// static
 void FieldTrial::EnableBenchmarking() {
   DCHECK_EQ(0u, FieldTrialList::GetFieldTrialCount());
   enable_benchmarking_ = true;