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

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

Index: third_party/WebKit/Source/core/fileapi/FileReaderLoader.h
diff --git a/third_party/WebKit/Source/core/fileapi/FileReaderLoader.h b/third_party/WebKit/Source/core/fileapi/FileReaderLoader.h
index 3bccac7eeacccfcaf26395af2c450ba5a282da33..a481f5b96751c602e332acbcdc2ea8a809d5cf7d 100644
--- a/third_party/WebKit/Source/core/fileapi/FileReaderLoader.h
+++ b/third_party/WebKit/Source/core/fileapi/FileReaderLoader.h
@@ -112,6 +112,8 @@ class CORE_EXPORT FileReaderLoader final : public ThreadableLoaderClient {
   FileReaderLoader(ReadType, FileReaderLoaderClient*);
 
   void Cleanup();
+  void ReportAdditionalMemoryUsageToV8(int64_t usage);
+  void UnreportMemoryUsageToV8();
 
   void Failed(FileError::ErrorCode);
   void ConvertToText();
@@ -150,6 +152,8 @@ class CORE_EXPORT FileReaderLoader final : public ThreadableLoaderClient {
   unsigned range_end_;
 
   FileError::ErrorCode error_code_;
+
+  int64_t memory_usage_reported_to_v8_ = 0;
 };
 
 }  // namespace blink