Add support for python pageset

tools/telemetry/telemetry/page/actions/wait.py

Index: tools/telemetry/telemetry/page/actions/wait.py
diff --git a/tools/telemetry/telemetry/page/actions/wait.py b/tools/telemetry/telemetry/page/actions/wait.py
index 4cb8742f267be96fd298c2d7a62128d489acc596..319e9bdcdacfbcf9883ce77ed8c6d8f4a4dc7a93 100644
--- a/tools/telemetry/telemetry/page/actions/wait.py
+++ b/tools/telemetry/telemetry/page/actions/wait.py
@@ -18,6 +18,15 @@ class WaitAction(page_action.PageAction):
     return (getattr(self, 'condition', None) == 'navigate' or
             getattr(self, 'condition', None) == 'href_change')
 
+  def UntilTextElementAvailable(self, text):
+    self.SetAttributes({'condition': 'element', 'text': text})
+
+  def UntilSelectorElementAvailable(self, selector):
+    self.SetAttributes({'condition': 'element', 'selector': selector})
+
+  def ForSeconds(self, seconds):
+    self.SetAttributes({'seconds': seconds})
+
   def RunAction(self, page, tab, previous_action):
     tab.ExecuteJavaScript(
         'console.time("' + self._GetUniqueTimelineMarkerName() + '")')