services/ui: Allow injecting the IO thread task runner for gpu channel.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index a6ba224890db29727486a1ada531d87055d337d8..9d0027e4bf7741a0259c9bb73a570b28d9db4981 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -636,7 +636,9 @@ void RenderThreadImpl::Init(
 #if defined(USE_AURA)
   if (IsRunningInMash()) {
     gpu_service_ =
-        ui::GpuService::Initialize(GetMojoShellConnection()->GetConnector());
+        ui::GpuService::Create(GetMojoShellConnection()->GetConnector());
+    gpu_service_->SetIOThreadTaskRunner(
+        ChildProcess::current()->io_task_runner());
   }
 #endif