Add function to register a synthetic trial with the trial hash.

chrome/browser/metrics/chrome_metrics_service_accessor.h

 // 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.
 
 #ifndef CHROME_BROWSER_METRICS_CHROME_METRICS_SERVICE_ACCESSOR_H_
 #define CHROME_BROWSER_METRICS_CHROME_METRICS_SERVICE_ACCESSOR_H_
 
+#include <stdint.h>
+#include <string>
+
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "chrome/browser/metrics/metrics_service_accessor.h"
 
 class ChromeBrowserMetricsServiceObserver;
 class Profile;
 
 namespace {
 class CrashesDOMHandler;
 class FlashDOMHandler;
@@ skipping 21 matching lines @@
   friend bool prerender::IsOmniboxEnabled(Profile* profile);
   friend class ::ChromeBrowserMetricsServiceObserver;
   friend class ChromeRenderMessageFilter;
   friend class ::CrashesDOMHandler;
   friend class DataReductionProxyChromeSettings;
   friend class extensions::ExtensionDownloader;
   friend class extensions::ManifestFetchData;
   friend class extensions::MetricsPrivateGetIsCrashReportingEnabledFunction;
   friend class ::FlashDOMHandler;
   friend class system_logs::ChromeInternalLogSource;
+  friend class UmaSessionStats;
 
   FRIEND_TEST_ALL_PREFIXES(ChromeMetricsServiceAccessorTest,
                            MetricsReportingEnabled);
   FRIEND_TEST_ALL_PREFIXES(ChromeMetricsServiceAccessorTest,
                            CrashReportingEnabled);
 
   // Returns true if prefs::kMetricsReportingEnabled is set.
   // TODO(asvitkine): Consolidate the method in MetricsStateManager.
   // TODO(asvitkine): This function does not report the correct value on
   // Android and ChromeOS, see http://crbug.com/362192.
   static bool IsMetricsReportingEnabled();
 
   // Returns true if crash reporting is enabled.  This is set at the platform
   // level for Android and ChromeOS, and otherwise is the same as
   // IsMetricsReportingEnabled for desktop Chrome.
   static bool IsCrashReportingEnabled();
 
   // Registers a field trial name and group to be used to annotate a UMA report
   // with a particular Chrome configuration state. A UMA report will be
   // annotated with this trial group if and only if all events in the report
   // were created after the trial is registered. Only one group name may be
   // registered at a time for a given trial name. Only the last group name that
   // is registered for a given trial name will be recorded. The values passed
   // in must not correspond to any real field trial in the code.
-  static bool RegisterSyntheticFieldTrial(const std::string& trial,
-                                          const std::string& group);
+  static bool RegisterSyntheticFieldTrial(const std::string& trial_name,
+                                          const std::string& group_name);
+
+  // Same as RegisterSyntheticFieldTrial above, but takes a hash for the trial
+  // name, rather than computing it from the string.
+  static bool RegisterSyntheticFieldTrialWithNameHash(
+      uint32_t trial_name_hash,
+      const std::string& group_name);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(ChromeMetricsServiceAccessor);
 };
 
 #endif  // CHROME_BROWSER_METRICS_CHROME_METRICS_SERVICE_ACCESSOR_H_