Remove calls to MessageLoop::current() in extensions.

extensions/browser/quota_service.cc

Index: extensions/browser/quota_service.cc
diff --git a/extensions/browser/quota_service.cc b/extensions/browser/quota_service.cc
index dbd11768bf76bc88cab7b25563208656aeedbd8d..67623fdc65e1abefe36cf7153237b3454da7e1da 100644
--- a/extensions/browser/quota_service.cc
+++ b/extensions/browser/quota_service.cc
@@ -4,8 +4,8 @@
 
 #include "extensions/browser/quota_service.h"
 
-#include "base/message_loop/message_loop.h"
 #include "base/stl_util.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "extensions/browser/extension_function.h"
 #include "extensions/common/error_utils.h"
 
@@ -23,7 +23,7 @@ const char kOverQuotaError[] = "This request exceeds the * quota.";
 namespace extensions {
 
 QuotaService::QuotaService() {
-  if (base::MessageLoop::current() != NULL) {  // Null in unit tests.
+  if (base::ThreadTaskRunnerHandle::IsSet()) {  // Not always set in unit tests.
     purge_timer_.Start(FROM_HERE,
                        base::TimeDelta::FromDays(kPurgeIntervalInDays),
                        this,