Measure usage of FormData.append(name, blob, filename)

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 722 matching lines @@
         V8TextTrackList_Item_Method = 829,
         TextInputFired = 830,
         V8TextEvent_Data_AttributeGetter = 831,
         V8TextEvent_InitTextEvent_Method = 832,
         V8SVGSVGElement_UseCurrentView_AttributeGetter = 833,
         V8SVGSVGElement_CurrentView_AttributeGetter = 834,
         ClientHintsDPR = 835,
         ClientHintsResourceWidth = 836,
         ClientHintsViewportWidth = 837,
         SRIElementIntegrityAttributeButIneligible = 838,
+        FormDataAppendFile = 839,
+        FormDataAppendFileWithFilename = 840,
+        FormDataAppendBlob = 841,
+        FormDataAppendBlobWithFilename = 842,
+        FormDataAppendNull = 843,
 
         // 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 83 matching lines @@
 
     bool hasRecordedMeasurement(Feature feature) const { return m_countBits.hasRecordedMeasurement(feature); }
 
     CountBits m_countBits;
     BitVector m_CSSFeatureBits;
 };
 
 } // namespace blink
 
 #endif // UseCounter_h