Remove handler from MessagePumpForIO::IOContext.

net/base/file_stream_context_win.cc

Index: net/base/file_stream_context_win.cc
diff --git a/net/base/file_stream_context_win.cc b/net/base/file_stream_context_win.cc
index 0294a1aa48617a94633c349ab0f756297418871f..cbcd907033577ff06ffa68a7477bd6ec89753c4d 100644
--- a/net/base/file_stream_context_win.cc
+++ b/net/base/file_stream_context_win.cc
@@ -44,10 +44,7 @@ FileStream::Context::Context(const scoped_refptr<base::TaskRunner>& task_runner)
       async_read_initiated_(false),
       async_read_completed_(false),
       io_complete_for_read_received_(false),
-      result_(0) {
-  io_context_.handler = this;
-  memset(&io_context_.overlapped, 0, sizeof(io_context_.overlapped));
-}
+      result_(0) {}
 
 FileStream::Context::Context(base::File file,
                              const scoped_refptr<base::TaskRunner>& task_runner)
@@ -60,8 +57,6 @@ FileStream::Context::Context(base::File file,
       async_read_completed_(false),
       io_complete_for_read_received_(false),
       result_(0) {
-  io_context_.handler = this;
-  memset(&io_context_.overlapped, 0, sizeof(io_context_.overlapped));
   if (file_.IsValid()) {
     DCHECK(file_.async());
     OnFileOpened();