Add a test for the "ephemeral_users_enabled" device policy

chrome/test/pyautolib/pyauto.py

Index: chrome/test/pyautolib/pyauto.py
diff --git a/chrome/test/pyautolib/pyauto.py b/chrome/test/pyautolib/pyauto.py
index ff7523289d9f0ea45c60558247dedae565fcb035..04945d74b6c24352187a5967315ab58e49131dd9 100755
--- a/chrome/test/pyautolib/pyauto.py
+++ b/chrome/test/pyautolib/pyauto.py
@@ -96,6 +96,9 @@ _REMOTE_PROXY = None
 _OPTIONS = None
 _BROWSER_PID = None
 
+# TODO(bartfab): Remove when crosbug.com/20709 is fixed.
+AUTO_CLEAR_LOCAL_STATE_MAGIC_FILE = '/root/.forget_usernames'
+
 
 class PyUITest(pyautolib.PyUITestBase, unittest.TestCase):
   """Base class for UI Test Cases in Python.
@@ -448,6 +451,30 @@ class PyUITest(pyautolib.PyUITestBase, unittest.TestCase):
     PyUITest.RunSuperuserActionOnChromeOS('RemoveAllCryptohomeVaults')
 
   @staticmethod
+  def TryToDisableLocalStateAutoClearingOnChromeOS():
+    """Disable clearing of the local state on session manager startup.
+
+    TODO(bartfab): Remove this method when crosbug.com/20709 is fixed.
+    """
+    PyUITest.RunSuperuserActionOnChromeOS('TryToDisableLocalStateAutoClearing')
+
+  @staticmethod
+  def TryToEnableLocalStateAutoClearingOnChromeOS():
+    """Enable clearing of the local state on session manager startup.
+
+    TODO(bartfab): Remove this method when crosbug.com/20709 is fixed.
+    """
+    PyUITest.RunSuperuserActionOnChromeOS('TryToEnableLocalStateAutoClearing')
+
+  @staticmethod
+  def IsLocalStateAutoClearingEnabledOnChromeOS():
+    """Check if the session manager is set to clear the local state on startup.
+
+    TODO(bartfab): Remove this method when crosbug.com/20709 is fixed.
+    """
+    return os.path.exists(AUTO_CLEAR_LOCAL_STATE_MAGIC_FILE)
+
+  @staticmethod
   def _IsInodeNew(path, old_inode):
     """Determine whether an inode has changed. POSIX only.
 
@@ -1292,7 +1319,7 @@ class PyUITest(pyautolib.PyUITestBase, unittest.TestCase):
       an instance of prefs_info.PrefsInfo
     """
     return prefs_info.PrefsInfo(
-        self._SendJSONRequest(0,
+        self._SendJSONRequest(-1,
                               json.dumps({'command': 'GetLocalStatePrefsInfo'}),
                               self.action_max_timeout_ms()))