Roll Chrome into Mojo.

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 369dfc1ad97515d62fbe2b73873fe87b8c90d058..85a596872b110292534629278e237e8130829979 100644
--- a/net/base/file_stream_context_win.cc
+++ b/net/base/file_stream_context_win.cc
@@ -9,6 +9,7 @@
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/task_runner.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
@@ -62,6 +63,10 @@ FileStream::Context::~Context() {
 int FileStream::Context::Read(IOBuffer* buf,
                               int buf_len,
                               const CompletionCallback& callback) {
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION("423948 FileStream::Context::Read"));
+
   DCHECK(!async_in_progress_);
 
   DWORD bytes_read;