[refactor] Split up SourceTracker into SourceTracker + EventsTracker.

chrome/browser/resources/net_internals/events_view.js

 // 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.
 
 /**
  * EventsView displays a filtered list of all events sharing a source, and
  * a details pane for the selected sources.
  *
  *  +----------------------++----------------+
  *  |      filter box      ||                |
@@ skipping 32 matching lines @@
 
     // Initialize the sub-views.
     var leftPane = new VerticalSplitView(new DivView(EventsView.TOPBAR_ID),
                                          new DivView(EventsView.LIST_BOX_ID));
 
     this.detailsView_ = new DetailsView(EventsView.DETAILS_LOG_BOX_ID);
 
     this.splitterView_ = new ResizableVerticalSplitView(
         leftPane, this.detailsView_, new DivView(EventsView.SIZER_ID));
 
-    g_browser.sourceTracker.addSourceEntryObserver(this);
+    SourceTracker.getInstance().addSourceEntryObserver(this);
 
     this.tableBody_ = $(EventsView.TBODY_ID);
 
     this.filterInput_ = $(EventsView.FILTER_INPUT_ID);
     this.filterCount_ = $(EventsView.FILTER_COUNT_ID);
 
     this.filterInput_.addEventListener('search',
         this.onFilterTextChanged_.bind(this), true);
 
     $(EventsView.SELECT_ALL_ID).addEventListener(
@@ skipping 611 matching lines @@
     var source1Text = source1.getSourceTypeString();
     var source2Text = source2.getSourceTypeString();
     var compareResult = source1Text.localeCompare(source2Text);
     if (compareResult != 0)
       return compareResult;
     return compareSourceId(source1, source2);
   }
 
   return EventsView;
 })();