Move timeline and importers to use telemetry.value.TraceValue

tools/perf/measurements/image_decoding.py

 # Copyright 2012 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 metrics import power
 from telemetry.page import page_measurement
 from telemetry.timeline import model
 from telemetry.value import scalar
 
 
@@ skipping 27 matching lines @@
             'devtools,webkit.console,blink.console')
 
   def StopBrowserAfterPage(self, browser, page):
     return not browser.tabs[0].ExecuteJavaScript("""
         window.chrome &&
             chrome.gpuBenchmarking &&
             chrome.gpuBenchmarking.clearImageCache;
     """)
 
   def MeasurePage(self, page, tab, results):
-    timeline_data = tab.browser.StopTracing()
-    timeline_model = model.TimelineModel(timeline_data)
+    trace_value = tab.browser.StopTracing()
+    timeline_model = model.TimelineModel(trace_value)
     self._power_metric.Stop(page, tab)
     self._power_metric.AddResults(tab, results)
 
     def _IsDone():
       return tab.EvaluateJavaScript('isDone')
 
     decode_image_events = timeline_model.GetAllEventsOfName('Decode Image')
 
     # If it is a real image page, then store only the last-minIterations
     # decode tasks.
@@ skipping 13 matching lines @@
         description='Average decode time for images in 4 different '
                     'formats: gif, png, jpg, and webp. The image files are '
                     'located at chrome/test/data/image_decoding.'))
     results.AddValue(scalar.ScalarValue(
         results.current_page, 'ImageLoading_avg', 'ms',
         tab.EvaluateJavaScript('averageLoadingTimeMs()')))
 
   def CleanUpAfterPage(self, page, tab):
     if tab.browser.is_tracing_running:
       tab.browser.StopTracing()