Force migrate all clients from multi-install back to single-install.

chrome/installer/util/master_preferences.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.
 //
 // This file contains functions processing master preference file used by
 // setup and first run.
 
 #ifndef CHROME_INSTALLER_UTIL_MASTER_PREFERENCES_H_
 #define CHROME_INSTALLER_UTIL_MASTER_PREFERENCES_H_
 
@@ skipping 152 matching lines @@
   std::string GetVariationsSeed() const;
 
   // Returns the variations seed signature entry from the master prefs.
   std::string GetVariationsSeedSignature() const;
 
   // Returns true iff the master preferences were successfully read from a file.
   bool read_from_file() const {
     return preferences_read_from_file_;
   }
 
-  bool install_chrome() const {
-    return chrome_;
-  }
+  bool install_chrome() const { return true; }
 
-  bool is_multi_install() const {
-    return multi_install_;
-  }
+  bool is_multi_install() const { return false; }
 
   // Returns a reference to this MasterPreferences' root dictionary of values.
   const base::DictionaryValue& master_dictionary() const {
     return *master_dictionary_.get();
   }
 
   // Returns a static preference object that has been initialized with the
   // CommandLine object for the current process.
   // NOTE: Must not be called before CommandLine::Init() is called!
   // OTHER NOTE: Not thread safe.
   static const MasterPreferences& ForCurrentProcess();
 
  private:
   void InitializeFromCommandLine(const base::CommandLine& cmd_line);
   void InitializeFromFilePath(const base::FilePath& prefs_path);
 
   // Initializes the instance from a given JSON string, returning true if the
   // string was successfully parsed.
   bool InitializeFromString(const std::string& json_data);
 
-  void InitializeProductFlags();
-
   // Enforces legacy preferences that should no longer be used, but could be
   // found in older master_preferences files.
   void EnforceLegacyPreferences();
 
   // Removes the specified string pref from the master preferences and returns
   // its value. Should be used for master prefs that shouldn't be automatically
   // copied over to profile preferences.
   std::string ExtractPrefString(const std::string& name) const;
 
   std::unique_ptr<base::DictionaryValue> master_dictionary_;
-  base::DictionaryValue* distribution_;
-  bool preferences_read_from_file_;
-  bool chrome_;
-  bool multi_install_;
+  base::DictionaryValue* distribution_ = nullptr;
+  bool preferences_read_from_file_ = false;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MasterPreferences);
 };
 
 }  // namespace installer
 
 #endif  // CHROME_INSTALLER_UTIL_MASTER_PREFERENCES_H_