test: Clean up site_login.py a bit.

client/site_tests/login_CryptohomeMounted/login_CryptohomeMounted.py

Index: client/site_tests/login_CryptohomeMounted/login_CryptohomeMounted.py
diff --git a/client/site_tests/login_CryptohomeMounted/login_CryptohomeMounted.py b/client/site_tests/login_CryptohomeMounted/login_CryptohomeMounted.py
index 30d6dc01ec244252cb0bd2ddabc9f4fe5e2c87f0..8fecd5f0eb3b1a72463f8ed18d811d691f16e8ee 100644
--- a/client/site_tests/login_CryptohomeMounted/login_CryptohomeMounted.py
+++ b/client/site_tests/login_CryptohomeMounted/login_CryptohomeMounted.py
@@ -14,19 +14,18 @@ class login_CryptohomeMounted(test.test):
         site_login.setup_autox(self)
 
     def run_once(self, script='autox_script.json', is_control=False):
-        logged_in = site_login.logged_in()
+        # Make sure that we're logged out initially -- this test is run
+        # multiple times, and we don't want to reuse the previous instance's
+        # session.
+        if site_login.logged_in():
+            site_login.attempt_logout()
 
-        if not logged_in:
-            # Test account information embedded into json file.
-            if not site_login.attempt_login(self, script):
-                raise error.TestFail('Could not login')
+        # Test account information embedded into json file.
+        site_login.attempt_login(self, script)
 
         if (not is_control and
             not site_cryptohome.is_mounted(allow_fail=is_control)):
             raise error.TestFail('CryptohomeIsMounted should return %s' %
                                  (not is_control))
 
-        # If we started logged out, log back out.
-        if not logged_in:
-            if not site_login.attempt_logout():
-                raise error.TestError('Could not log out')
+        site_login.attempt_logout()