Add an installer crash key for the currently installed version.

chrome/installer/setup/installer_crash_reporting.h

 // Copyright 2015 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_SETUP_INSTALLER_CRASH_REPORTING_H_
 #define CHROME_INSTALLER_SETUP_INSTALLER_CRASH_REPORTING_H_
 
 #include <vector>
 
 #include "base/debug/crash_logging.h"
 
 namespace base {
 class CommandLine;
+class Version;
 }  // namespace base
 
 namespace installer {
 
 class InstallerState;
 
 // Sets up the crash reporting system for the installer.
 void ConfigureCrashReporting(const InstallerState& installer_state);
 
 // Registers all crash keys used by the installer.
 size_t RegisterCrashKeys();
 
 // Sets all crash keys that are available during process startup. These do not
 // vary during execution so this function will not need to be called more than
 // once.
 void SetInitialCrashKeys(const InstallerState& installer_state);
 
 // Sets crash keys for the switches given in |command_line|.
 void SetCrashKeysFromCommandLine(const base::CommandLine& command_line);
 
+// Sets a crash key recording the version of the product which was present
+// before the installer was run.
+void SetCurrentVersionCrashKey(const base::Version* current_version);
+
 }  // namespace installer
 
 #endif  // CHROME_INSTALLER_SETUP_INSTALLER_CRASH_REPORTING_H_