[tools/perf] Rename mobile_facebook_login to facebook_login

This CL also renames mobile_facebook_login.LoginAccount to
facebook_login.LoginWithMobileSite.

Motivation: later we will add a login method for facebook desktop, hence
generalize this module to support both.

BUG=589726

Review-Url: https://codereview.chromium.org/2166743005
Cr-Commit-Position: refs/heads/master@{#407122}

tools/perf/page_sets/login_helpers/mobile_facebook_login.py → tools/perf/page_sets/login_helpers/facebook_login.py

@@ -4,7 +4,7 @@
 from page_sets.login_helpers import login_utils
 
 
-def LoginAccount(
+def LoginWithMobileSite(
     action_runner, credential,
     credentials_path=login_utils.DEFAULT_CREDENTIAL_PATH):
   """Logs in into mobile Facebook account.

tools/perf/page_sets/mobile_facebook_page.py

@@ -2,10 +2,11 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-from page_sets.login_helpers import mobile_facebook_login
+from page_sets.login_helpers import facebook_login
 
 from telemetry.page import page as page_module
 
+
 class MobileFacebookPage(page_module.Page):
   def __init__(self, url, page_set, shared_page_state_class, name='facebook'):
     super(MobileFacebookPage, self).__init__(
@@ -13,6 +14,6 @@ class MobileFacebookPage(page_module.Page):
         credentials_path='data/credentials.json',
         shared_page_state_class=shared_page_state_class)
   def RunNavigateSteps(self, action_runner):
-    mobile_facebook_login.LoginAccount(action_runner, 'facebook3',
+    facebook_login.LoginWithMobileSite(action_runner, 'facebook3',
                                        self.credentials_path)
     super(MobileFacebookPage, self).RunNavigateSteps(action_runner)