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

tools/telemetry/telemetry/browser_credentials.py

Index: tools/telemetry/telemetry/browser_credentials.py
diff --git a/tools/telemetry/telemetry/browser_credentials.py b/tools/telemetry/telemetry/browser_credentials.py
index 2950aeda2f8abb836dc0500aa29c57523218f38a..69501b37c34fc8aaa62e45f0a47d88e0da3492da 100644
--- a/tools/telemetry/telemetry/browser_credentials.py
+++ b/tools/telemetry/telemetry/browser_credentials.py
@@ -28,6 +28,13 @@ class BrowserCredentials(object):
     assert backend.credentials_type not in self._backends
     self._backends[backend.credentials_type] = backend
 
+  def IsLoggedIn(self, credentials_type):
+    if credentials_type not in self._backends:
+      raise Exception('Unrecognized credentials type: %s', credentials_type)
+    if credentials_type not in self._credentials:
+      return False
+    return self._backends[credentials_type].IsLoggedIn()
+
   def CanLogin(self, credentials_type):
     if credentials_type not in self._backends:
       raise Exception('Unrecognized credentials type: %s', credentials_type)
@@ -62,6 +69,13 @@ class BrowserCredentials(object):
       self._extra_credentials[credentials_type][k] = v
     self._RebuildCredentials()
 
+  def _ResetLoggedInState(self):
+    """Makes the backends think we're not logged in even though we are.
+    Should only be used in unit tests to simulate --dont-override-profile.
+    """
+    for backend in self._backends.keys():
+      self._backends[backend]._ResetLoggedInState() # pylint: disable=W0212
+
   def _RebuildCredentials(self):
     credentials = {}
     if self._credentials_path == None: