Catch ERROR_INVALID_WINDOW_HANDLE in the quit chrome script.

In the mini_installer test framework, the script quit_chrome.py quits Chrome by sending a WM_CLOSE message to each window of Chrome. Once we send the message to a window, it's possible that the handles to other windows may become invalid (see buildbot error message http://goo.gl/16VmkX). Fix this by catching ERROR_INVALID_WINDOW_HANDLE.

NOTRY=True
BUG=264859
TEST=
1) Uninstall Chrome (if it's installed.) 
2) Build Chrome with Release mode and make sure that mini_installer.exe is created.
3) Go to src\chrome\test\mini_installer 
4) Edit quit_chrome.py. Add line "hwnd = 12345" before the line "win32gui.PostMessage(hwnd, win32con.WM_CLOSE, 0, 0)". Add line "print 'ok'" after the line "raise". Then save.
5) Run "python test_installer.py config\config.config --build-dir=<build-dir> --target=Release" where <build-dir> is the path to main build directory (the parent of the Release directory). It should print "ok" repeatedly.

Review URL: https://chromiumcodereview.appspot.com/23498025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@222098 0039d316-1c4b-4281-b951-d872f2087c98

chrome/test/mini_installer/quit_chrome.py

@@ -9,10 +9,12 @@ the process terminates.
 """
 
 import optparse
+import pywintypes
 import sys
 import time
 import win32con
 import win32gui
+import winerror
 
 import chrome_helper
 
@@ -34,7 +36,12 @@ def CloseWindows(process_path):
       return True
 
     for hwnd in chrome_helper.GetWindowHandles(process_ids):
+      try:
         win32gui.PostMessage(hwnd, win32con.WM_CLOSE, 0, 0)
+      except pywintypes.error as error:
+        # It's normal that some window handles have become invalid.
+        if error.args[0] != winerror.ERROR_INVALID_WINDOW_HANDLE:
+          raise
     time.sleep(0)
   return False