Make quiesence test best-effort for the blink_style benchmark

tools/perf/measurements/blink_style.py

Index: tools/perf/measurements/blink_style.py
diff --git a/tools/perf/measurements/blink_style.py b/tools/perf/measurements/blink_style.py
index f89ab980085c4fc912debb5ce4d6af451428a12b..f76cdf2575deb9ab4a9a84d50c1ec5ce9d691780 100644
--- a/tools/perf/measurements/blink_style.py
+++ b/tools/perf/measurements/blink_style.py
@@ -4,8 +4,8 @@
 
 from itertools import starmap
 from collections import defaultdict
-
 from telemetry.core import util
+from telemetry.core import exceptions
 from telemetry.page import page_test
 from telemetry.value import scalar
 
@@ -19,7 +19,7 @@ class BlinkStyle(page_test.PageTest):
 
   def WillNavigateToPage(self, page, tab):
     self._controller = timeline_controller.TimelineController()
-    self._controller.trace_categories = 'blink,benchmark,blink.console'
+    self._controller.trace_categories = 'blink_style,blink.console'
     self._controller.SetUp(page, tab)
     self._controller.Start(tab)
 
@@ -28,9 +28,12 @@ class BlinkStyle(page_test.PageTest):
       self._controller.CleanUp(tab)
 
   def ValidateAndMeasurePage(self, page, tab, results):
-    tab.WaitForDocumentReadyStateToBeComplete()
-    if not util.WaitFor(tab.HasReachedQuiescence, 30):
-      raise page_test.MeasurementFailure('Failed to reach quiesence.')
+    tab.ExecuteJavaScript('console.time("wait-for-quiescence");')
+    try:
+      util.WaitFor(tab.HasReachedQuiescence, 15)
+    except exceptions.TimeoutException:

[dtu, 2015/04/27 13:02:20]

? Can you add a comment explaining why you want to wait at most 15 seconds
instead of always waiting until quiescence?

+      pass
+    tab.ExecuteJavaScript('console.timeEnd("wait-for-quiescence");')
 
     tab.ExecuteJavaScript(
         'console.time("style-update");'
@@ -62,7 +65,10 @@ class BlinkStyle(page_test.PageTest):
       if (event.name == 'Document::updateStyle'
           and event.start >= marker.start
           and event.end <= marker.end):
-        access_count = event.args['resolverAccessCount']
+        access_count = event.get('resolverAccessCount')
+        if access_count is None:
+          # absent in earlier versions
+          continue
         min_access_count = 50
 
         if access_count >= min_access_count: