Use ScopedTaskEnvironment instead of MessageLoopForUI in chromeos tests.

chromeos/network/geolocation_handler_unittest.cc

Index: chromeos/network/geolocation_handler_unittest.cc
diff --git a/chromeos/network/geolocation_handler_unittest.cc b/chromeos/network/geolocation_handler_unittest.cc
index 9d5dc9f2cdd84534fcfee8e4e3a55cb662c63f93..13375ac2dcced383533e1fa92e2659da37c2b1f1 100644
--- a/chromeos/network/geolocation_handler_unittest.cc
+++ b/chromeos/network/geolocation_handler_unittest.cc
@@ -7,10 +7,10 @@
 #include <memory>
 
 #include "base/macros.h"
-#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/values.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/shill_manager_client.h"
@@ -21,8 +21,9 @@ namespace chromeos {
 
 class GeolocationHandlerTest : public testing::Test {
  public:
-  GeolocationHandlerTest() : manager_test_(NULL) {
-  }
+  GeolocationHandlerTest()
+      : scoped_task_environment_(
+            base::test::ScopedTaskEnvironment::MainThreadType::UI) {}
 
   ~GeolocationHandlerTest() override {}
 
@@ -94,9 +95,9 @@ class GeolocationHandlerTest : public testing::Test {
   }
 
  protected:
-  base::MessageLoopForUI message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
   std::unique_ptr<GeolocationHandler> geolocation_handler_;
-  ShillManagerClient::TestInterface* manager_test_;
+  ShillManagerClient::TestInterface* manager_test_ = nullptr;
   WifiAccessPointVector wifi_access_points_;
   CellTowerVector cell_towers_;