Use timer task runner for V8PerIsolate tasks

gin/per_isolate_data.cc

Index: gin/per_isolate_data.cc
diff --git a/gin/per_isolate_data.cc b/gin/per_isolate_data.cc
index 261782eeaa5d469b6cb734c51b8c559d45c3c041..dd4ce9daab94f29b1aadacb5c697c06007d7bd55 100644
--- a/gin/per_isolate_data.cc
+++ b/gin/per_isolate_data.cc
@@ -21,13 +21,15 @@ using v8::ObjectTemplate;
 
 namespace gin {
 
-PerIsolateData::PerIsolateData(Isolate* isolate,
-                               ArrayBuffer::Allocator* allocator,
-                               IsolateHolder::AccessMode access_mode)
+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_(base::ThreadTaskRunnerHandle::Get()) {
+      task_runner_(task_runner) {
   isolate_->SetData(kEmbedderNativeGin, this);
 }