Enable OAuth2 by default.

ClientLogin will be supposedly turned off on Apr 20.

R=maruel@chromium.org
BUG=356813

Review URL: https://codereview.chromium.org/1095033002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@294899 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/auth.py b/auth.py
index 15fc15d..cc1b82b 100644
--- a/auth.py
+++ b/auth.py
@@ -111,7 +111,7 @@
   """
   default = lambda val, d: val if val is not None else d
   return AuthConfig(
-      default(use_oauth2, _should_use_oauth2()),
+      default(use_oauth2, True),
       default(save_cookies, True),
       default(use_local_webserver, not _is_headless()),
       default(webserver_port, 8090),
@@ -481,14 +481,6 @@
 ## Private functions.
 
 
-def _should_use_oauth2():
-  """Default value for use_oauth2 config option.
-
-  Used to selectively enable OAuth2 by default.
-  """
-  return os.path.exists(os.path.join(DEPOT_TOOLS_DIR, 'USE_OAUTH2'))
-
-
 def _is_headless():
   """True if machine doesn't seem to have a display."""
   return sys.platform == 'linux2' and not os.environ.get('DISPLAY')