[telemetry] Move tab from RunState to PageState.

tools/perf/measurements/image_decoding.py

 # Copyright (c) 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 telemetry.page import page_measurement
 
 
 class ImageDecoding(page_measurement.PageMeasurement):
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArgs('--enable-gpu-benchmarking')
 
   def WillNavigateToPage(self, page, tab):
     tab.ExecuteJavaScript("""
         if (window.chrome &&
             chrome.gpuBenchmarking &&
             chrome.gpuBenchmarking.clearImageCache) {
           chrome.gpuBenchmarking.clearImageCache();
         }
     """)
     tab.StartTimelineRecording()
 
-  def NeedsBrowserRestartAfterEachRun(self, tab):
-    return not tab.ExecuteJavaScript("""
+  def NeedsBrowserRestartAfterEachRun(self, browser):
+    return not browser.tabs[0].ExecuteJavaScript("""
         window.chrome &&
             chrome.gpuBenchmarking &&
             chrome.gpuBenchmarking.clearImageCache;
     """)
 
   def MeasurePage(self, page, tab, results):
     tab.StopTimelineRecording()
     def _IsDone():
       return tab.EvaluateJavaScript('isDone')
 
@@ skipping 10 matching lines @@
       decode_image_events = decode_image_events[-min_iterations:]
 
     durations = [d.duration for d in decode_image_events]
     if not durations:
       results.Add('ImageDecoding_avg', 'ms', 'unsupported')
       return
     image_decoding_avg = sum(durations) / len(durations)
     results.Add('ImageDecoding_avg', 'ms', image_decoding_avg)
     results.Add('ImageLoading_avg', 'ms',
                 tab.EvaluateJavaScript('averageLoadingTimeMs()'))