Add a use counter and histogram to FileReaderSync.

third_party/WebKit/Source/core/fileapi/FileReaderSync.h

 /*
  * Copyright (C) 2010 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 31 matching lines @@
 class ExceptionState;
 class ExecutionContext;
 class FileReaderLoader;
 class ScriptState;
 
 class FileReaderSync final : public GarbageCollected<FileReaderSync>,
                              public ScriptWrappable {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
-  static FileReaderSync* create() { return new FileReaderSync(); }
+  static FileReaderSync* create(ExecutionContext* context) {
+    return new FileReaderSync(context);
+  }
 
   DOMArrayBuffer* readAsArrayBuffer(ScriptState*, Blob*, ExceptionState&);
   String readAsBinaryString(ScriptState*, Blob*, ExceptionState&);
   String readAsText(ScriptState* scriptState, Blob* blob, ExceptionState& ec) {
     return readAsText(scriptState, blob, "", ec);
   }
   String readAsText(ScriptState*,
                     Blob*,
                     const String& encoding,
                     ExceptionState&);
   String readAsDataURL(ScriptState*, Blob*, ExceptionState&);
 
   DEFINE_INLINE_TRACE() {}
 
  private:
-  FileReaderSync();
+  explicit FileReaderSync(ExecutionContext*);
 
   void startLoading(ExecutionContext*,
                     FileReaderLoader&,
                     const Blob&,
                     ExceptionState&);
 };
 
 }  // namespace blink
 
 #endif  // FileReaderSync_h