telemetry: Stop measuring tough_path_rendering_cases chalkboard test after it stops

tools/perf/page_sets/tough_path_rendering_cases.py

Index: tools/perf/page_sets/tough_path_rendering_cases.py
diff --git a/tools/perf/page_sets/tough_path_rendering_cases.py b/tools/perf/page_sets/tough_path_rendering_cases.py
index c565e7e61f29fa7639215e83fad655e8151789d8..4227fed45263f049bea6458a56cee5d2c55728da 100644
--- a/tools/perf/page_sets/tough_path_rendering_cases.py
+++ b/tools/perf/page_sets/tough_path_rendering_cases.py
@@ -15,10 +15,12 @@ class ToughPathRenderingCasesPage(page_module.Page):
 class ChalkboardPage(page_module.Page):
 
   def RunPageInteractions(self, action_runner):
+    action_runner.tab.WaitForDocumentReadyStateToBeComplete()

[Stephen White, 2016/05/19 15:26:41]

Hmmm! Note to self: we should probably add this to the "Pirates" demo too (under
tough_filters_cases).

     with action_runner.CreateInteraction('ClickStart'):
       action_runner.EvaluateJavaScript(
           'document.getElementById("StartButton").click()')
-      action_runner.Wait(20)
+      action_runner.WaitForJavaScriptCondition(
+          'document.getElementById("FinalTime").innerText != ""')

[Stephen White, 2016/05/19 15:26:41]

It would be really cool to gather the actual value here, if available.

[Kimmo Kinnunen, 2016/05/20 10:54:42]

So would this be another "benchmark" in addition to smoothness?
If I understand correctly "smoothness" measures "smoothness" numbers, not for
example this number?

I can try to create a new benchmark that would produce the chalkboar result
number. I can try to add those tiger numbers to that or similar benchmark. 

[Stephen White, 2016/05/20 13:25:12]

I had assumed it could just be added to the existing values collected without
creating a 
new benchmark type. But to be honest, I don't know enough about Telemetry to
say.
Maybe the infrastructure folks could shed some light?
It was definitely not a requirement to get your stuff landed, just something
I've 
wanted to collect. frame_times is the only value we alert on for these tests,
and
I think that's fine for now.

 
 class ToughPathRenderingCasesPageSet(story.StorySet):