Retrieve client_id from GoogleUpdateSettings when its missing from Local State.

chrome/installer/util/google_update_settings.h

 // Copyright (c) 2012 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_INSTALLER_UTIL_GOOGLE_UPDATE_SETTINGS_H_
 #define CHROME_INSTALLER_UTIL_GOOGLE_UPDATE_SETTINGS_H_
 
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "base/version.h"
 #include "chrome/installer/util/util_constants.h"
+#include "components/metrics/client_info.h"
 
 class AppRegistrationData;
 class BrowserDistribution;
 
 namespace installer {
 class ChannelInfo;
 class InstallationState;
 }
 
 // This class provides accessors to the Google Update 'ClientState' information
@@ skipping 54 matching lines @@
   // crash dumps to Google. This information is collected by the web server
   // used to download the chrome installer.
   static bool GetCollectStatsConsentAtLevel(bool system_install);
 
   // Sets the user consent to send UMA and crash dumps to Google. Returns
   // false if the setting could not be recorded.
   static bool SetCollectStatsConsentAtLevel(bool system_install,
                                             bool consented);
 #endif
 
-  // Returns the metrics client id backed up in the registry. If none found,
-  // returns empty string.
-  static bool LoadMetricsClientId(std::string* metrics_id);
+  // Returns the metrics client info backed up in the registry. NULL
+  // if-and-only-if the client_id couldn't be retrieved (failure to retrieve
+  // other fields only makes them keep their default value). A non-null return
+  // will NEVER contain an empty client_id field.
+  static scoped_ptr<metrics::ClientInfo> LoadMetricsClientInfo();
 
-  // Stores a backup of the metrics client id in the registry.
-  static bool StoreMetricsClientId(const std::string& metrics_id);
+  // Stores a backup of the metrics client info in the registry. Storing a
+  // |client_info| with an empty client id will effectively void the backup.
+  static void StoreMetricsClientInfo(const metrics::ClientInfo& client_info);
 
   // Sets the machine-wide EULA consented flag required on OEM installs.
   // Returns false if the setting could not be recorded.
   static bool SetEULAConsent(const installer::InstallationState& machine_state,
                              BrowserDistribution* dist,
                              bool consented);
 
   // Returns the last time chrome was run in days. It uses a recorded value
   // set by SetLastRunTime(). Returns -1 if the value was not found or if
   // the value is corrupted.
@@ skipping 201 matching lines @@
   // this will do nothing to |experiment_labels|. This will return true if the
   // label did not exist, or was successfully read.
   static bool ReadExperimentLabels(bool system_install,
                                    base::string16* experiment_labels);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(GoogleUpdateSettings);
 };
 
 #endif  // CHROME_INSTALLER_UTIL_GOOGLE_UPDATE_SETTINGS_H_