swap timed wait for whenPolymerReady function

tools/perf/page_sets/polymer.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.
 from telemetry.page import page as page_module
 from telemetry.page import page_set as page_set_module
 
 class PolymerPage(page_module.Page):
 
   def __init__(self, url, page_set):
     super(PolymerPage, self).__init__(
@@ skipping 94 matching lines @@
       url=('http://www.polymer-project.org/components/paper-elements/demo.html#'
           + anchor),
       page_set=page_set)
     self.scrolling_page = scrolling_page
     self.iframe_js = 'document.querySelector("sampler-scaffold").$.frame'
 
   def RunNavigateSteps(self, action_runner):
     #FIXME(wiltzius) workaround for crbug.com/391672
     action_runner.ExecuteJavaScript('window.location.href="about:blank";')
     super(PolymerSampler, self).RunNavigateSteps(action_runner)
-    #FIXME(wiltzius) this should wait for iframe to load and all load
-    # animations to end
-    action_runner.Wait(5)
+    waitForLoadJS = """
+      window.Polymer.whenPolymerReady(function() {
+        %s.contentWindow.Polymer.whenPolymerReady(function() {
+          window.__polymer_ready = true;
+        })
+      });
+      """ % self.iframe_js
+    action_runner.ExecuteJavaScript(waitForLoadJS)
+    action_runner.WaitForJavaScriptCondition(
+        'window.__polymer_ready')
 
   def RunSmoothness(self, action_runner):
     #TODO(wiltzius) Add interactions for input elements and shadow pages
     if self.scrolling_page:
       # Only bother scrolling the page if its been marked as worthwhile
       self.ScrollContentPane(action_runner)
     self.TouchEverything(action_runner)
 
   def ScrollContentPane(self, action_runner):
     element_function = (self.iframe_js + '.contentDocument.querySelector('
@@ skipping 87 matching lines @@
     for p in TAPPABLE_PAGES:
       self.AddPage(PolymerSampler(self, p))
 
     # Polymer Sampler subpages that are interesting to scroll
     SCROLLABLE_PAGES = [
         # crbug.com/394756
         # 'core-scroll-header-panel',
         ]
     for p in SCROLLABLE_PAGES:
       self.AddPage(PolymerSampler(self, p, scrolling_page=True))