virtualenv_wrapper: Simplify _CHROMITE_DIR discovery.

Based on what we do in constants.py.

BUG=None
TEST=Unittest.

Change-Id: Ic37001b7e6e3c42bb4b95e6a3003b761acdd28a3
Reviewed-on: https://chromium-review.googlesource.com/482526
Commit-Ready: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Allen Li <ayatane@chromium.org>
diff --git a/scripts/virtualenv_wrapper.py b/scripts/virtualenv_wrapper.py
index 95710b9..5a8a79a 100755
--- a/scripts/virtualenv_wrapper.py
+++ b/scripts/virtualenv_wrapper.py
@@ -13,15 +13,8 @@
 
 import wrapper
 
-
-def _FindChromiteDir():
-  path = os.path.dirname(os.path.realpath(__file__))
-  while not os.path.exists(os.path.join(path, 'PRESUBMIT.cfg')):
-    path = os.path.dirname(path)
-  return path
-
-
-_CHROMITE_DIR = _FindChromiteDir()
+_CHROMITE_DIR = os.path.realpath(
+    os.path.join(os.path.abspath(__file__), '..', '..'))
 
 # _VIRTUALENV_DIR contains the scripts for working with venvs
 _VIRTUALENV_DIR = os.path.join(_CHROMITE_DIR, '..', 'infra_virtualenv')