Add PDF compositor service

content/utility/utility_thread_impl.cc

Index: content/utility/utility_thread_impl.cc
diff --git a/content/utility/utility_thread_impl.cc b/content/utility/utility_thread_impl.cc
index 681bffd0854f0357c795ede5e988430efe068688..fedbd1e712fc8c361753f2d2d2a54788b9d5e4d6 100644
--- a/content/utility/utility_thread_impl.cc
+++ b/content/utility/utility_thread_impl.cc
@@ -68,6 +68,11 @@ void UtilityThreadImpl::ReleaseProcessIfNeeded() {
   }
 }
 
+scoped_refptr<base::SingleThreadTaskRunner>
+UtilityThreadImpl::GetIOTaskRunner() {
+  return ChildProcess::current()->io_task_runner();
+}
+
 void UtilityThreadImpl::EnsureBlinkInitialized() {
   if (blink_platform_impl_ || IsInBrowserProcess()) {
     // We can only initialize WebKit on one thread, and in single process mode