Tell V8 about the extra memory being held by FileReader objects.

third_party/WebKit/Source/core/fileapi/FileReaderLoader.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 94 matching lines @@
 
   FileError::ErrorCode GetErrorCode() const { return error_code_; }
 
   void SetEncoding(const String&);
   void SetDataType(const String& data_type) { data_type_ = data_type; }
 
  private:
   FileReaderLoader(ReadType, FileReaderLoaderClient*);
 
   void Cleanup();
+  void ReportAdditionalMemoryUsageToV8(int64_t usage);
+  void UnreportMemoryUsageToV8();
 
   void Failed(FileError::ErrorCode);
   void ConvertToText();
   void ConvertToDataURL();
 
   static FileError::ErrorCode HttpStatusCodeToErrorCode(int);
 
   ReadType read_type_;
   FileReaderLoaderClient* client_;
   WTF::TextEncoding encoding_;
@@ skipping 18 matching lines @@
   // dynamically grow. Otherwise, m_totalBytes is set to the total size and
   // the buffer for receiving data of m_totalBytes is allocated and never grow
   // even when extra data is appeneded.
   long long total_bytes_;
 
   bool has_range_;
   unsigned range_start_;
   unsigned range_end_;
 
   FileError::ErrorCode error_code_;
+
+  int64_t memory_usage_reported_to_v8_ = 0;
 };
 
 }  // namespace blink
 
 #endif  // FileReaderLoader_h