Disable FileReaderSync in service workers.

third_party/WebKit/Source/core/frame/Deprecation.cpp

 // Copyright 2016 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.
 
 #include "core/frame/Deprecation.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/frame/FrameConsole.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 376 matching lines @@
       return String::format(
           "The service worker responded to the navigation request with a "
           "redirected response. This will result in an error in %s.",
           milestoneString(M59));
 
     case UseCounter::CSSSelectorInternalMediaControlsOverlayCastButton:
       return willBeRemoved(
           "-internal-media-controls-overlay-cast-button selector", M59,
           "5714245488476160");
 
-    case UseCounter::FileReaderSyncInServiceWorker:
-      return willBeRemoved("FileReaderSync in service workers", M59,
-                           "5739144722513920");
-
     case UseCounter::CSSZoomReset:
       return willBeRemoved("\"zoom: reset\"", M59, "4997605029314560");
 
     case UseCounter::CSSZoomDocument:
       return willBeRemoved("\"zoom: document\"", M59, "4997605029314560");
 
     case UseCounter::SelectionAddRangeIntersect:
       return "The behavior that Selection.addRange() merges existing Range and "
              "the specified Range was removed. See "
              "https://www.chromestatus.com/features/6680566019653632 for more "
@@ skipping 23 matching lines @@
                                    "the 'script-src' directive for Workers",
                                    M60, "5922594955984896");
 
     // Features that aren't deprecated don't have a deprecation message.
     default:
       return String();
   }
 }
 
 }  // namespace blink