Use timer task runner for V8PerIsolate tasks

gin/isolate_holder.cc

Index: gin/isolate_holder.cc
diff --git a/gin/isolate_holder.cc b/gin/isolate_holder.cc
index 04449d26ab5657712c8c35d64da65b20424852ea..e38190c4285dd49997452b6336b61c0518fcc9f4 100644
--- a/gin/isolate_holder.cc
+++ b/gin/isolate_holder.cc
@@ -27,10 +27,13 @@ namespace {
 v8::ArrayBuffer::Allocator* g_array_buffer_allocator = nullptr;
 }  // namespace
 
-IsolateHolder::IsolateHolder() : IsolateHolder(AccessMode::kSingleThread) {
-}
+IsolateHolder::IsolateHolder(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
+    : IsolateHolder(std::move(task_runner), AccessMode::kSingleThread) {}
 
-IsolateHolder::IsolateHolder(AccessMode access_mode)
+IsolateHolder::IsolateHolder(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+    AccessMode access_mode)
     : access_mode_(access_mode) {
   v8::ArrayBuffer::Allocator* allocator = g_array_buffer_allocator;
   CHECK(allocator) << "You need to invoke gin::IsolateHolder::Initialize first";
@@ -41,7 +44,8 @@ IsolateHolder::IsolateHolder(AccessMode access_mode)
                                        base::SysInfo::AmountOfVirtualMemory());
   params.array_buffer_allocator = allocator;
   isolate_ = v8::Isolate::New(params);
-  isolate_data_.reset(new PerIsolateData(isolate_, allocator, access_mode));
+  isolate_data_.reset(
+      new PerIsolateData(isolate_, allocator, access_mode, task_runner));
   isolate_memory_dump_provider_.reset(new V8IsolateMemoryDumpProvider(this));
 #if defined(OS_WIN)
   {