Overinstall mismatch, Launch the existing chrome instead...

chrome/installer/util/util_constants.h

 // Copyright (c) 2006-2009 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.
 //
 // Defines all install related constants that need to be used by Chrome as
 // well as Chrome Installer.
 
 #ifndef CHROME_INSTALLER_UTIL_UTIL_CONSTANTS_H_
 #define CHROME_INSTALLER_UTIL_UTIL_CONSTANTS_H_
 
 namespace installer_util {
 
 // Return status of installer
 enum InstallStatus {
   FIRST_INSTALL_SUCCESS, // Successfully installed Chrome for the first time
   INSTALL_REPAIRED,      // Same version reinstalled for repair
   NEW_VERSION_UPDATED,   // Chrome successfully updated to new version
+  EXISTING_VERSION_LAUNCHED,  // No work done, just launched existing chrome
   HIGHER_VERSION_EXISTS, // Higher version of Chrome already exists
   USER_LEVEL_INSTALL_EXISTS, // User level install already exists
   SYSTEM_LEVEL_INSTALL_EXISTS, // Machine level install already exists
   INSTALL_FAILED,        // Install/update failed
   SETUP_PATCH_FAILED,    // Failed to patch setup.exe
   OS_NOT_SUPPORTED,      // Current OS not supported
   OS_ERROR,              // OS API call failed
   TEMP_DIR_FAILED,       // Unable to get Temp directory
   UNCOMPRESSION_FAILED,  // Failed to uncompress Chrome archive
   INVALID_ARCHIVE,       // Something wrong with the installer archive
@@ skipping 68 matching lines @@
 extern const wchar_t kSxSSuffix[];
 
 extern const wchar_t kUninstallStringField[];
 extern const wchar_t kUninstallDisplayNameField[];
 extern const wchar_t kUninstallMetricsName[];
 extern const wchar_t kUninstallInstallationDate[];
 
 }  // namespace installer_util
 
 #endif  // CHROME_INSTALLER_UTIL_UTIL_CONSTANTS_H_