Update from https://crrev.com/307330

net/url_request/url_request.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/url_request/url_request.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
@@ skipping 750 matching lines @@
     // Caller is not too bright.  I guess we've done what they asked.
     return true;
   }
 
   // Once the request fails or is cancelled, read will just return 0 bytes
   // to indicate end of stream.
   if (!status_.is_success()) {
     return true;
   }
 
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+  tracked_objects::ScopedTracker tracking_profile1(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION("423948 URLRequest::Read1"));
+
   bool rv = job_->Read(dest, dest_size, bytes_read);
   // If rv is false, the status cannot be success.
   DCHECK(rv || status_.status() != URLRequestStatus::SUCCESS);
+
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+  tracked_objects::ScopedTracker tracking_profile2(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION("423948 URLRequest::Read2"));
+
   if (rv && *bytes_read <= 0 && status_.is_success())
     NotifyRequestCompleted();
   return rv;
 }
 
 void URLRequest::StopCaching() {
   DCHECK(job_.get());
   job_->StopCaching();
 }
 
@@ skipping 441 matching lines @@
       new base::debug::StackTrace(NULL, 0);
   *stack_trace_copy = stack_trace;
   stack_trace_.reset(stack_trace_copy);
 }
 
 const base::debug::StackTrace* URLRequest::stack_trace() const {
   return stack_trace_.get();
 }
 
 }  // namespace net