Tolerate a null WebScheduler in utility process V8 initialization

gin/per_isolate_data.cc

 // Copyright 2013 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 "gin/per_isolate_data.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 11 matching lines @@
 namespace gin {
 
 PerIsolateData::PerIsolateData(
     Isolate* isolate,
     ArrayBuffer::Allocator* allocator,
     IsolateHolder::AccessMode access_mode,
     scoped_refptr<base::SingleThreadTaskRunner> task_runner)
     : isolate_(isolate),
       allocator_(allocator),
       access_mode_(access_mode),
-      task_runner_(task_runner) {
+      task_runner_(
+          task_runner ? task_runner : base::ThreadTaskRunnerHandle::Get()) {
   isolate_->SetData(kEmbedderNativeGin, this);
 }
 
 PerIsolateData::~PerIsolateData() {
   isolate_->SetData(kEmbedderNativeGin, NULL);
 }
 
 PerIsolateData* PerIsolateData::From(Isolate* isolate) {
   return static_cast<PerIsolateData*>(isolate->GetData(kEmbedderNativeGin));
 }
@@ skipping 73 matching lines @@
   else
     return NULL;
 }
 
 void PerIsolateData::EnableIdleTasks(
     std::unique_ptr<V8IdleTaskRunner> idle_task_runner) {
   idle_task_runner_ = std::move(idle_task_runner);
 }
 
 }  // namespace gin