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..3fa973bbfcd3ce56aafcd033ed0cff257b4403ac 100644
--- a/third_party/WebKit/Source/core/fileapi/FileReaderLoader.h
+++ b/third_party/WebKit/Source/core/fileapi/FileReaderLoader.h
@@ -112,10 +112,13 @@ 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();
-  void ConvertToDataURL();
+  String ConvertToText();
+  String ConvertToDataURL();
+  void SetStringResult(const String&);
 
   static FileError::ErrorCode HttpStatusCodeToErrorCode(int);
 
@@ -144,7 +147,7 @@ class CORE_EXPORT FileReaderLoader final : public ThreadableLoaderClient {
   // the buffer for receiving data of m_totalBytes is allocated and never grow
   // even when extra data is appeneded.
   long long total_bytes_;
-
+  int64_t memory_usage_reported_to_v8_ = 0;

[michaeln, 2017/04/28 00:54:25]

i can switch more of the data members to initialize here too

[dmurph, 2017/04/28 20:39:44]

That would be great actually. I like that style.

   bool has_range_;
   unsigned range_start_;
   unsigned range_end_;