Measure usage of createObjectURL and srcObject

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 1308 matching lines @@
         PaymentAddressCareOf = 1580,
         XSSAuditorBlockedScript = 1581,
         XSSAuditorBlockedEntirePage = 1582,
         XSSAuditorDisabled = 1583,
         XSSAuditorEnabledFilter = 1584,
         XSSAuditorEnabledBlock = 1585,
         XSSAuditorInvalid = 1586,
         SVGCursorElement = 1587,
         SVGCursorElementHasClient = 1588,
         V8NavigatorUserMediaError_ConstraintName_AttributeGetter = 1589,
+        CreateObjectURLBlob = 1590,
+        CreateObjectURLMediaSource = 1591,
+        CreateObjectURLMediaStream = 1592,
 
         // 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 62 matching lines @@
     private:
         // Tracks what features/properties need to be reported to the legacy histograms.
         BitVector m_featureBits;
         BitVector m_CSSBits;
     } m_legacyCounter;
 };
 
 } // namespace blink
 
 #endif // UseCounter_h