[UMA] Include field trial tuples in the UMA upload.

chrome/browser/metrics/metrics_log.h

Index: chrome/browser/metrics/metrics_log.h
diff --git a/chrome/browser/metrics/metrics_log.h b/chrome/browser/metrics/metrics_log.h
index 5935139a58133d6e8119b08d9ab250e35254c7f8..4d7e452d13ff234d338eb31af1213cbfdb6bb8f2 100644
--- a/chrome/browser/metrics/metrics_log.h
+++ b/chrome/browser/metrics/metrics_log.h
@@ -13,6 +13,7 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/metrics/field_trial.h"
 #include "chrome/common/metrics/metrics_log_base.h"
 
 struct AutocompleteLog;
@@ -71,6 +72,17 @@ class MetricsLog : public MetricsLogBase {
   void RecordIncrementalStabilityElements(
       const std::vector<webkit::WebPluginInfo>& plugin_list);
 
+ protected:
+  // Exposed for the sake of mocking in test code.
+
+  // Returns the PrefService from which to log metrics data.
+  virtual PrefService* GetPrefService();
+
+  // Fills |field_trial_ids| with the list of initialized field trials name and
+  // group ids.
+  virtual void GetFieldTrialIds(
+    std::vector<base::FieldTrial::NameGroupId>* field_trial_ids) const;
+
  private:
   FRIEND_TEST_ALL_PREFIXES(MetricsLogTest, ChromeOSStabilityData);