Use timer task runner for V8PerIsolate tasks

gin/shell_runner_unittest.cc

 // Copyright 2014 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/shell_runner.h"
 
 #include "base/compiler_specific.h"
 #include "base/message_loop/message_loop.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "gin/array_buffer.h"
 #include "gin/converter.h"
 #include "gin/public/isolate_holder.h"
 #include "gin/v8_initializer.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
 #include "gin/public/isolate_holder.h"
 #endif
 
 using v8::Isolate;
 using v8::Object;
 using v8::Script;
 using v8::String;
 
 namespace gin {
 
 TEST(RunnerTest, Run) {
   base::MessageLoop message_loop;
   std::string source = "this.result = 'PASS';\n";
 
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
   gin::V8Initializer::LoadV8Snapshot();
   gin::V8Initializer::LoadV8Natives();
 #endif
 
   gin::IsolateHolder::Initialize(gin::IsolateHolder::kStrictMode,
                                  gin::IsolateHolder::kStableV8Extras,
                                  gin::ArrayBufferAllocator::SharedInstance());
-  gin::IsolateHolder instance;
+  gin::IsolateHolder instance(base::ThreadTaskRunnerHandle::Get());
 
   ShellRunnerDelegate delegate;
   Isolate* isolate = instance.isolate();
   ShellRunner runner(&delegate, isolate);
   Runner::Scope scope(&runner);
   runner.Run(source, "test_data.js");
 
   std::string result;
   EXPECT_TRUE(Converter<std::string>::FromV8(isolate,
       runner.global()->Get(StringToV8(isolate, "result")),
       &result));
   EXPECT_EQ("PASS", result);
 }
 
 }  // namespace gin