Add Wait* API to ActionRunner to wrap over WaitAction.

tools/perf/page_sets/webrtc_cases.py

Index: tools/perf/page_sets/webrtc_cases.py
diff --git a/tools/perf/page_sets/webrtc_cases.py b/tools/perf/page_sets/webrtc_cases.py
index 54c8f48b4fa72170e089a49ba466eb1b52935117..24aaab374d17dfc78088f6c16e9c58f121fe4161 100644
--- a/tools/perf/page_sets/webrtc_cases.py
+++ b/tools/perf/page_sets/webrtc_cases.py
@@ -24,10 +24,7 @@ class Page1(WebrtcCasesPage):
 
   def RunWebrtc(self, action_runner):
     action_runner.NavigateToPage(self)
-    action_runner.RunAction(WaitAction(
-      {
-        'seconds': 10
-      }))
+    action_runner.Wait(10)
     action_runner.ExecuteJavaScript('checkForErrors();')
 
 
@@ -45,18 +42,12 @@ class Page2(WebrtcCasesPage):
       {
         'selector': 'button[id="btn1"]'
       }))
-    action_runner.RunAction(WaitAction(
-      {
-        'seconds': 2
-      }))
+    action_runner.Wait(2)
     action_runner.RunAction(ClickElementAction(
       {
         'selector': 'button[id="btn2"]'
       }))
-    action_runner.RunAction(WaitAction(
-      {
-        'seconds': 10
-      }))
+    action_runner.Wait(10)
     action_runner.RunAction(ClickElementAction(
       {
         'selector': 'button[id="btn3"]'
@@ -67,18 +58,12 @@ class Page2(WebrtcCasesPage):
       {
         'selector': 'button[id="btn1"]'
       }))
-    action_runner.RunAction(WaitAction(
-      {
-        'seconds': 2
-      }))
+    action_runner.Wait(2)
     action_runner.RunAction(ClickElementAction(
       {
         'selector': 'button[id="btn2"]'
       }))
-    action_runner.RunAction(WaitAction(
-      {
-        'seconds': 10
-      }))
+    action_runner.Wait(10)
     action_runner.RunAction(ClickElementAction(
       {
         'selector': 'button[id="btn3"]'