Add missing TaskScheduler on tests using RendereWidgetHostImpl

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 90afecd8290a9633cee6f2b9de069c68d3f5951a..dc0c48ebb9edace1d115fabe9baa698efc4d8542 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -299,6 +299,8 @@ RenderWidgetHostImpl::RenderWidgetHostImpl(RenderWidgetHostDelegate* delegate,
   CHECK_NE(MSG_ROUTING_NONE, routing_id_);
   latency_tracker_.SetDelegate(delegate_);
 
+  DCHECK(base::TaskScheduler::GetInstance())
+      << "Ref. Prerequisite section of post_task.h";
 #if defined(OS_WIN)
   // Update the display color profile cache so that it is likely to be up to
   // date when the renderer process requests the color profile.