Add an accessor to HeadlessBrowser for the IO thread

headless/lib/browser/headless_browser_impl.cc

 // Copyright 2015 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 "headless/lib/browser/headless_browser_impl.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
@@ skipping 45 matching lines @@
 
 HeadlessBrowserImpl::~HeadlessBrowserImpl() {}
 
 HeadlessBrowserContext::Builder
 HeadlessBrowserImpl::CreateBrowserContextBuilder() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   return HeadlessBrowserContext::Builder(this);
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
+HeadlessBrowserImpl::BrowserFileThread() const {
+  return content::BrowserThread::GetTaskRunnerForThread(
+      content::BrowserThread::FILE);
+}
+
+scoped_refptr<base::SingleThreadTaskRunner>
+HeadlessBrowserImpl::BrowserIOThread() const {
+  return content::BrowserThread::GetTaskRunnerForThread(
+      content::BrowserThread::IO);
+}
+
+scoped_refptr<base::SingleThreadTaskRunner>
 HeadlessBrowserImpl::BrowserMainThread() const {
   return content::BrowserThread::GetTaskRunnerForThread(
       content::BrowserThread::UI);
 }
 
-scoped_refptr<base::SingleThreadTaskRunner>
-HeadlessBrowserImpl::BrowserFileThread() const {
-  return content::BrowserThread::GetTaskRunnerForThread(
-      content::BrowserThread::FILE);
-}
-
 void HeadlessBrowserImpl::Shutdown() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
   weak_ptr_factory_.InvalidateWeakPtrs();
 
   // Destroy all browser contexts.
   browser_contexts_.clear();
 
   BrowserMainThread()->PostTask(FROM_HERE,
                                 base::MessageLoop::QuitWhenIdleClosure());
@@ skipping 112 matching lines @@
 
   // Child processes should not end up here.
   base::CommandLine command_line(options.argc, options.argv);
   DCHECK(!command_line.HasSwitch(switches::kProcessType));
 #endif
   return RunContentMain(std::move(options),
                         std::move(on_browser_start_callback));
 }
 
 }  // namespace headless