Adding instrumentation to locate the source of jankiness.

storage/browser/fileapi/file_writer_delegate.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 "storage/browser/fileapi/file_writer_delegate.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file_util_proxy.h"
 #include "base/message_loop/message_loop.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/sequenced_task_runner.h"
 #include "base/threading/thread_restrictions.h"
 #include "net/base/net_errors.h"
 #include "storage/browser/fileapi/file_stream_writer.h"
 #include "storage/browser/fileapi/file_system_context.h"
 #include "storage/common/fileapi/file_system_util.h"
 
 namespace storage {
 
 static const int kReadBufSize = 32768;
@@ skipping 61 matching lines @@
 }
 
 void FileWriterDelegate::OnSSLCertificateError(net::URLRequest* request,
                                                const net::SSLInfo& ssl_info,
                                                bool fatal) {
   NOTREACHED();
   OnError(base::File::FILE_ERROR_SECURITY);
 }
 
 void FileWriterDelegate::OnResponseStarted(net::URLRequest* request) {
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "423948 FileWriterDelegate::OnResponseStarted"));
+
   DCHECK_EQ(request_.get(), request);
   if (!request->status().is_success() || request->GetResponseCode() != 200) {
     OnError(base::File::FILE_ERROR_FAILED);
     return;
   }
   Read();
 }
 
 void FileWriterDelegate::OnReadCompleted(net::URLRequest* request,
                                          int bytes_read) {
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "423948 FileWriterDelegate::OnReadCompleted"));
+
   DCHECK_EQ(request_.get(), request);
   if (!request->status().is_success()) {
     OnError(base::File::FILE_ERROR_FAILED);
     return;
   }
   OnDataReceived(bytes_read);
 }
 
 void FileWriterDelegate::Read() {
   bytes_written_ = 0;
@@ skipping 122 matching lines @@
   if (error == base::File::FILE_OK && flush_error != net::OK) {
     // If the Flush introduced an error, overwrite the status.
     // Otherwise, keep the original error status.
     error = NetErrorToFileError(flush_error);
     progress_status = GetCompletionStatusOnError();
   }
   write_callback_.Run(error, bytes_written, progress_status);
 }
 
 }  // namespace storage