Remove use of deprecated MessageLoop methods in extensions.

extensions/renderer/script_context_set.cc

Index: extensions/renderer/script_context_set.cc
diff --git a/extensions/renderer/script_context_set.cc b/extensions/renderer/script_context_set.cc
index 33df67e58d19b97e2136d370cf38994c8c364f05..adefb3838becf53f84c3e4b2443eaf9dc34a45e5 100644
--- a/extensions/renderer/script_context_set.cc
+++ b/extensions/renderer/script_context_set.cc
@@ -4,7 +4,9 @@
 
 #include "extensions/renderer/script_context_set.h"
 
-#include "base/message_loop/message_loop.h"
+#include "base/location.h"
+#include "base/single_thread_task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "content/public/common/url_constants.h"
 #include "content/public/renderer/render_frame.h"
 #include "extensions/common/extension.h"
@@ -61,7 +63,7 @@ ScriptContext* ScriptContextSet::Register(
 void ScriptContextSet::Remove(ScriptContext* context) {
   if (contexts_.erase(context)) {
     context->Invalidate();
-    base::MessageLoop::current()->DeleteSoon(FROM_HERE, context);
+    base::ThreadTaskRunnerHandle::Get()->DeleteSoon(FROM_HERE, context);
   }
 }