[Telemetry] fix google_credentials_backend_unittest.py and facebook_credentials_backend_unittest.py.

tools/telemetry/telemetry/form_based_credentials_backend.py

Index: tools/telemetry/telemetry/form_based_credentials_backend.py
diff --git a/tools/telemetry/telemetry/form_based_credentials_backend.py b/tools/telemetry/telemetry/form_based_credentials_backend.py
index 69c89ce8173486d988d710c3a70c95111e433a52..8ec51d7daf7ddbb338974f186ec3bd86f1b6dcfa 100644
--- a/tools/telemetry/telemetry/form_based_credentials_backend.py
+++ b/tools/telemetry/telemetry/form_based_credentials_backend.py
@@ -62,6 +62,15 @@ class FormBasedCredentialsBackend(object):
   def password_input_id(self):
     raise NotImplementedError()
 
+  def IsLoggedIn(self):
+    return self._logged_in
+
+  def _ResetLoggedInState(self):
+    """Makes the backend think we're not logged in even though we are.
+    Should only be used in unit tests to simulate --dont-override-profile.
+    """
+    self._logged_in = False
+
   def LoginNeeded(self, tab, config):
     """Logs in to a test account.