Pass correct --parent-window value to native messaging hosts

chrome/test/data/native_messaging/native_hosts/echo.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.
 
 # A simple native client in python.
 # All this client does is echo the text it receives back at the extension.
 
 import os
+import platform
 import sys
 import struct
 
 def WriteMessage(message):
   try:
     sys.stdout.write(struct.pack("I", len(message)))
     sys.stdout.write(message)
     sys.stdout.flush()
     return True
   except IOError:
     return False
 
 def Main():
   message_number = 0
 
+  caller_url = None;

[miket_OOO, 2014/01/07 17:15:11]

Begone, semicolon!

[Sergey Ulanov, 2014/01/07 20:56:10]

Done.

+  parent_window = None
+
   if len(sys.argv) < 2:
     sys.stderr.write("URL of the calling application is not specified.\n")
-    return;
+    return 1
   for arg in sys.argv[1:]:
-    if not arg.startswith('--'):
+    if arg.startswith('--'):
+      if arg.startswith('--parent-window='):

[miket_OOO, 2014/01/07 17:15:11]

Not a big deal, but it makes me sad when I see manual parsing of command-line
arguments when wonderful libraries like
http://docs.python.org/2/library/argparse.html#module-argparse exist. OK to keep
as-is -- or maybe add a TODO for next time?

[Sergey Ulanov, 2014/01/07 20:56:10]

Added TODO. FWIW argparse is available only starting Python 2.7 and we are still
using 2.6 on Windows. This script could use optparse (which is available in 2.6,
deprecated in 2.7), but it doesn't seem to worth spending time on it right now
given that we would want to switch to argparse in the future.

+        parent_window = long(arg[len('--parent-window='):])
+    elif caller_url == None:
       caller_url = arg
-      break
+
+  if platform.system() == 'Windows':
+    import win32gui
+    if not win32gui.IsWindow(parent_window):
+      sys.stderr.write('Invalid --parent-window.\n')
+      return 1
 
   while 1:
     # Read the message type (first 4 bytes).
     text_length_bytes = sys.stdin.read(4)
 
     if len(text_length_bytes) == 0:
       break
 
     # Read the message length (4 bytes).
     text_length = struct.unpack('i', text_length_bytes)[0]
@@ skipping 14 matching lines @@
     if 'stopHostTest' in text:
       # Using os.close() here because sys.stdin.close() doesn't really close
       # the pipe (it just marks it as closed, but doesn't close the file
       # descriptor).
       os.close(sys.stdin.fileno())
       WriteMessage('{"stopped": true }')
       sys.exit(0)
 
     message_number += 1
 
-    if not WriteMessage(
-        '{{"id": {0}, "echo": {1}, "caller_url": "{2}"}}'.format(
-          message_number, text, caller_url).encode('utf-8')):
+    message = '{{"id": {0}, "echo": {1}, "caller_url": "{2}"}}'.format(
+          message_number, text, caller_url).encode('utf-8')
+    if not WriteMessage(message):
       break
 
 if __name__ == '__main__':
-  Main()
+  sys.exit(Main())