[telemetry] Move tab from RunState to PageState.

tools/perf/metrics/io.py

 # Copyright 2013 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 Metric
 
 class IOMetric(Metric):
   """IO-related metrics, obtained via telemetry.core.Browser."""
 
   @classmethod
   def CustomizeBrowserOptions(cls, options):
     options.AppendExtraBrowserArgs('--no-sandbox')
 
   def Start(self, page, tab):
     raise NotImplementedError()
 
   def Stop(self, page, tab):
     raise NotImplementedError()
 
   def AddResults(self, tab, results):
     # This metric currently only returns summary results, not per-page results.
     raise NotImplementedError()
 
-  def AddSummaryResults(self, tab, results):
+  def AddSummaryResults(self, browser, results):
     """Add summary results to the results object."""
-    io_stats = tab.browser.io_stats
+    io_stats = browser.io_stats
     if not io_stats['Browser']:
       return
 
     def AddSummariesForProcessType(process_type_io, process_type_trace):
       """For a given process type, add all relevant summary results.
 
       Args:
         process_type_io: Type of process (eg Browser or Renderer).
         process_type_trace: String to be added to the trace name in the results.
       """
@@ skipping 15 matching lines @@
       if 'WriteTransferCount' in io_stats[process_type_io]:
         results.AddSummary('write_bytes_' + process_type_trace, 'kb',
                            io_stats[process_type_io]
                            ['WriteTransferCount'] / 1024,
                            data_type='unimportant')
 
     AddSummariesForProcessType('Browser', 'browser')
     AddSummariesForProcessType('Renderer', 'renderer')
     AddSummariesForProcessType('Gpu', 'gpu')