[VS Addin] Don't fail installation if win32 platform is missing.

visual_studio/NativeClientVSAddIn/InstallerResources/install.py

 #!/usr/bin/env python
 # 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.
 
 """Copies necessary add-in files into place to install the add-in.
 
 This script will copy the necessary files for the Visual Studio add-in
 to where Visual Studio can find them. It assumes the current directory
 contains the necessary files to copy.
@@ skipping 298 matching lines @@
     raise
   else:
     print "\nInstallation complete!\n"
 
   return 0
 
 if __name__ == '__main__':
   rtn = 1
   try:
     rtn = main()
-  except InstallError as e:
+  except (create_ppapi_platform.Error, InstallError) as e:
     print
     print e
   except shutil.Error as e:
     print "Error while copying file. Please ensure file is not in use."
     print e
   except WindowsError as e:
     if e.winerror == 5:
       print e
       print("The install script failed to write to the files mentioned above")
       if ctypes.windll.shell32.IsUserAnAdmin() != 1:
         print("Please try running as administrator.")
       else:
         print("Please check for any running programs that might "
               "have them locked.")
     else:
       raise
   sys.exit(rtn)