Disable FileReaderSync in service 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 1420 matching lines @@
     V8DeprecatedStorageInfo_QueryUsageAndQuota_Method = 1808,
     V8DeprecatedStorageInfo_RequestQuota_Method = 1809,
     V8DeprecatedStorageQuota_QueryUsageAndQuota_Method = 1810,
     V8DeprecatedStorageQuota_RequestQuota_Method = 1811,
     V8FileReaderSync_Constructor = 1812,
     UncancellableTouchEventPreventDefaulted = 1813,
     UncancellableTouchEventDueToMainThreadResponsivenessPreventDefaulted = 1814,
     V8HTMLVideoElement_Poster_AttributeGetter = 1815,
     V8HTMLVideoElement_Poster_AttributeSetter = 1816,
     NotificationPermissionRequestedIframe = 1817,
-    FileReaderSyncInServiceWorker = 1818,
     PresentationReceiverInsecureOrigin = 1819,
     PresentationReceiverSecureOrigin = 1820,
     PresentationRequestInsecureOrigin = 1821,
     PresentationRequestSecureOrigin = 1822,
     RtcpMuxPolicyNegotiate = 1823,
     DOMClobberedVariableAccessed = 1824,
     HTMLDocumentCreateProcessingInstruction = 1825,
     FetchResponseConstructionWithStream = 1826,
     LocationOrigin = 1827,
     DocumentOrigin = 1828,
@@ skipping 149 matching lines @@
     // 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