Cleanup interaction creation and add ExecuteJavaScript to action_runner.py

tools/perf/page_sets/webrtc_cases.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 # pylint: disable=W0401,W0614
 from telemetry.page.actions.all_page_actions import *
 from telemetry.page import page as page_module
 from telemetry.page import page_set as page_set_module
 
 
 class WebrtcCasesPage(page_module.Page):
@@ skipping 10 matching lines @@
     super(Page1, self).__init__(
       url='file://webrtc/local-video.html',
       page_set=page_set)
 
   def RunWebrtc(self, action_runner):
     action_runner.NavigateToPage(self)
     action_runner.RunAction(WaitAction(
       {
         'seconds': 10
       }))
-    action_runner.RunAction(JavascriptAction(
-      {
-        'expression': 'checkForErrors();'
-      }))
+    action_runner.ExecuteJavaScript('checkForErrors();')
 
 
 class Page2(WebrtcCasesPage):
 
   """ Why: Loopback video call using the PeerConnection API. """
 
   def __init__(self, page_set):
     super(Page2, self).__init__(
       url='file://third_party/webrtc/samples/js/demos/html/pc1.html',
       page_set=page_set)
@@ skipping 46 matching lines @@
 class WebrtcCasesPageSet(page_set_module.PageSet):
 
   """ WebRTC tests for Real-time audio and video communication. """
 
   def __init__(self):
     super(WebrtcCasesPageSet, self).__init__(
       serving_dirs=['third_party/webrtc/samples/js'])
 
     self.AddPage(Page1(self))
     self.AddPage(Page2(self))