[tools/perf] Delete unused variable

tools/perf/measurements/draw_properties.py

 # Copyright 2015 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_test
 from telemetry.timeline import model
 from telemetry.timeline import tracing_config
 from telemetry.value import scalar
 
 
 class DrawProperties(page_test.PageTest):
 
   def __init__(self):
     super(DrawProperties, self).__init__()
 
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArgs([
         '--enable-prefer-compositing-to-lcd-text',
     ])
 
   def WillNavigateToPage(self, page, tab):
+    del page  # unused
     config = tracing_config.TracingConfig()
     config.tracing_category_filter.AddDisabledByDefault(
         'disabled-by-default-cc.debug.cdp-perf')
     config.enable_chrome_trace = True
     tab.browser.platform.tracing_controller.StartTracing(config)
 
   def ComputeAverageOfDurations(self, timeline_model, name):
     events = timeline_model.GetAllEventsOfName(name)
     event_durations = [d.duration for d in events]
     assert event_durations, 'Failed to find durations'
 
     duration_sum = sum(event_durations)
     duration_count = len(event_durations)
     duration_avg = duration_sum / duration_count
     return duration_avg
 
   def ValidateAndMeasurePage(self, page, tab, results):
+    del page  # unused
     timeline_data = tab.browser.platform.tracing_controller.StopTracing()
     timeline_model = model.TimelineModel(timeline_data)
 
     pt_avg = self.ComputeAverageOfDurations(
         timeline_model,
         'LayerTreeHostCommon::ComputeVisibleRectsWithPropertyTrees')
 
     results.AddValue(scalar.ScalarValue(
         results.current_page, 'PT_avg_cost', 'ms', pt_avg,
         description='Average time spent processing property trees'))
 
   def DidRunPage(self, platform):
     tracing_controller = platform.tracing_controller
     if tracing_controller.is_tracing_running:
       tracing_controller.StopTracing()