Add Wait* API to ActionRunner to wrap over WaitAction.

tools/perf/page_sets/tough_scheduling_cases.py

Index: tools/perf/page_sets/tough_scheduling_cases.py
diff --git a/tools/perf/page_sets/tough_scheduling_cases.py b/tools/perf/page_sets/tough_scheduling_cases.py
index 4cc5cb4f9e5330d67dad89046c019c67a89aeaca..e044fc9378417e26b4166bced5ecc00b3fdf21cf 100644
--- a/tools/perf/page_sets/tough_scheduling_cases.py
+++ b/tools/perf/page_sets/tough_scheduling_cases.py
@@ -291,10 +291,7 @@ class Page19(ToughSchedulingCasesPage):
       page_set=page_set)
 
   def RunSmoothness(self, action_runner):
-    action_runner.RunAction(WaitAction(
-      {
-        "seconds": 3
-      }))
+    action_runner.Wait(3)
 
 class Page20(ToughSchedulingCasesPage):
 
@@ -448,4 +445,3 @@ class ToughSchedulingCasesPageSet(page_set_module.PageSet):
       slow_handler=True,
       bounce=True,
       page_set=self))
-