clovis: Enable the disable-by-default-blink.debug.layout tracing category.

tools/android/loading/user_satisfied_lens.py

 # Copyright 2016 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.
 
 """Identifies key events related to user satisfaction.
 
 Several lenses are defined, for example FirstTextPaintLens and
 FirstSignificantPaintLens.
 """
 import logging
@@ skipping 73 matching lines @@
     return [rq for rq in request_track.GetEvents()
             if rq.end_msec <= time_ms]
 
 
 class _FirstEventLens(_UserSatisfiedLens):
   """Helper abstract subclass that defines users first event manipulations."""
   # pylint can't handle abstract subclasses.
   # pylint: disable=abstract-method
 
   @classmethod
+  def _CheckCategory(cls, tracing_track, category):
+    assert category in tracing_track.Categories(), (
+        'The "%s" category must be enabled.' % category)
+
+  @classmethod
   def _ExtractFirstTiming(cls, times):
     if not times:
       return float('inf')
     if len(times) != 1:
       # TODO(mattcary): in some cases a trace has two first paint events. Why?
       logging.error('%d %s with spread of %s', len(times),
                     str(cls), max(times) - min(times))
     return float(min(times))
 
 
 class FirstTextPaintLens(_FirstEventLens):
   """Define satisfaction by the first text paint.
 
   This event is taken directly from a trace.
   """
+  _EVENT_CATEGORY = 'blink.user_timing'
   def _CalculateTimes(self, tracing_track):
+    self._CheckCategory(tracing_track, self._EVENT_CATEGORY)
     first_paints = [e.start_msec for e in tracing_track.GetEvents()
-                    if e.Matches('blink.user_timing', 'firstPaint')]
+                    if e.Matches(self._EVENT_CATEGORY, 'firstPaint')]
     self._satisfied_msec = self._event_msec = \
         self._ExtractFirstTiming(first_paints)
 
 
 class FirstContentfulPaintLens(_FirstEventLens):
   """Define satisfaction by the first contentful paint.
 
   This event is taken directly from a trace. Internally to chrome it's computed
   by filtering out things like background paint from firstPaint.
   """
+  _EVENT_CATEGORY = 'blink.user_timing'
   def _CalculateTimes(self, tracing_track):
+    self._CheckCategory(tracing_track, self._EVENT_CATEGORY)
     first_paints = [e.start_msec for e in tracing_track.GetEvents()
-                    if e.Matches('blink.user_timing', 'firstContentfulPaint')]
+                    if e.Matches(self._EVENT_CATEGORY, 'firstContentfulPaint')]
     self._satisfied_msec = self._event_msec = \
        self._ExtractFirstTiming(first_paints)
 
 
 class FirstSignificantPaintLens(_FirstEventLens):
   """Define satisfaction by the first paint after a big layout change.
 
   Our satisfaction time is that of the layout change, as all resources must have
   been loaded to compute the layout. Our event time is that of the next paint as
   that is the observable event.
   """
   FIRST_LAYOUT_COUNTER = 'LayoutObjectsThatHadNeverHadLayout'

[mattcary, 2016/04/27 08:00:04]

While you're in here add an underscore to FIRST_LAYOUT_COUNTER to keep naming
consistent.

-
+  _EVENT_CATEGORY = 'disabled-by-default-blink.debug.layout'
   def _CalculateTimes(self, tracing_track):
+    self._CheckCategory(tracing_track, self._EVENT_CATEGORY)
     sync_paint_times = []
     layouts = []  # (layout item count, msec).
     for e in tracing_track.GetEvents():
       # TODO(mattcary): is this the right paint event? Check if synchronized
       # paints appear at the same time as the first*Paint events, above.
       if e.Matches('blink', 'FrameView::SynchronizedPaint'):
         sync_paint_times.append(e.start_msec)
       if ('counters' in e.args and
           self.FIRST_LAYOUT_COUNTER in e.args['counters']):
         layouts.append((e.args['counters'][self.FIRST_LAYOUT_COUNTER],
                         e.start_msec))
-    assert layouts, ('No layout events, was the disabled-by-default-blink'
-                     '.debug.layout category enabled?')
+    assert layouts, 'No layout events'
     layouts.sort(key=operator.itemgetter(0), reverse=True)
     self._satisfied_msec = layouts[0][1]
     self._event_msec = self._ExtractFirstTiming([
         min(t for t in sync_paint_times if t > self._satisfied_msec)])