Measure EventSource usage in Document and Workers.

third_party/WebKit/Source/core/frame/UseCounter.h

 /*
  * Copyright (C) 2012 Google, Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1261 matching lines @@
         SlotChangeEventAddListener = 1468,
         CSSValueAppearanceButtonRendered = 1469,
         CSSValueAppearanceButtonForAnchor = 1470,
         CSSValueAppearanceButtonForButton = 1471,
         CSSValueAppearanceButtonForOtherButtons = 1472,
         CSSValueAppearanceTextFieldRendered = 1473,
         CSSValueAppearanceTextFieldForSearch = 1474,
         CSSValueAppearanceTextFieldForTextField = 1475,
         RTCPeerConnectionGetStats = 1476,
         SVGSMILAnimationAppliedEffect = 1477,
+        EventSourceDocument = 1478,
+        EventSourceWorker = 1479,
 
         PerformanceResourceTimingSizes = 1478,

[Mike West, 2016/07/28 12:34:11]

Yours need to come after this.

[Mike West, 2016/07/28 12:34:39]

(Maybe remove the extraneous whitespace, as it's confusing. :)

[mlamouri (slow - plz ping), 2016/07/28 12:39:43]

Yes indeed, this empty line tricked me well :)

 
         // Add new features immediately above this line. Don't change assigned
         // numbers of any item, and don't reuse removed slots.
         // Also, run update_use_counter_feature_enum.py in chromium/src/tools/metrics/histograms/
         // to update the UMA mapping.
         NumberOfFeatures, // This enum value must be last.
     };
 
     // "count" sets the bit for this feature to 1. Repeated calls are ignored.
     static void count(const Frame*, Feature);
@@ skipping 74 matching lines @@
     friend class UseCounterTest;
     static int m_muteCount;
 
     CountBits m_countBits;
     BitVector m_CSSFeatureBits;
 };
 
 } // namespace blink
 
 #endif // UseCounter_h