[System Health] Change scrolling behaviour for news sites.

tools/perf/page_sets/system_health/browsing_stories.py

Index: tools/perf/page_sets/system_health/browsing_stories.py
diff --git a/tools/perf/page_sets/system_health/browsing_stories.py b/tools/perf/page_sets/system_health/browsing_stories.py
index ef283c7d2088283069b3b6f0324b8a77e93a0d0d..e0753eac5e45faa94a841248a35aa9f98f5ca1e2 100644
--- a/tools/perf/page_sets/system_health/browsing_stories.py
+++ b/tools/perf/page_sets/system_health/browsing_stories.py
@@ -76,9 +76,10 @@ class _NewsBrowsingStory(_BrowsingStory):
 
   def _ReadNewsItem(self, action_runner):
     action_runner.tab.WaitForDocumentReadyStateToBeComplete()
-    action_runner.Wait(self.ITEM_READ_TIME_IN_SECONDS)
+    action_runner.Wait(self.ITEM_READ_TIME_IN_SECONDS/2)

[rnephew (Reviews Here), 2016/11/15 22:08:43]

We could also have it wait the entire time before and after, but that will
increase the run time of the SH tests; but assuming my reason why we didn't
catch it is correct it would increase the likelihood of us catching it..

[perezju, 2016/11/16 09:58:05]

Note: This is doing integer division. So before it was waiting 3 seconds in
total, it now waits 2 * (3 / 2) = 2 * 1 = 2 seconds!

I think what you want is:

  action_runner.Wait(self.ITEM_READ_TIME_IN_SECONDS / 2.0)

     action_runner.RepeatableBrowserDrivenScroll(
         repeat_count=self.ITEM_SCROLL_REPEAT)
+    action_runner.Wait(self.ITEM_READ_TIME_IN_SECONDS/2)
 
   def _ScrollMainPage(self, action_runner):
     action_runner.tab.WaitForDocumentReadyStateToBeComplete()