Use ScopedTaskEnvironment instead of MessageLoopForUI in components tests.

components/component_updater/timer_unittest.cc

Index: components/component_updater/timer_unittest.cc
diff --git a/components/component_updater/timer_unittest.cc b/components/component_updater/timer_unittest.cc
index 2c80e84d2a2acb7ac8d0dcd919844a4acfb629f5..c90ae0251470ce769b2699104112b89c922721a1 100644
--- a/components/component_updater/timer_unittest.cc
+++ b/components/component_updater/timer_unittest.cc
@@ -4,8 +4,8 @@
 
 #include <string>
 
-#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/time/time.h"
 #include "components/component_updater/timer.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -16,11 +16,13 @@ namespace component_updater {
 
 class ComponentUpdaterTimerTest : public testing::Test {
  public:
-  ComponentUpdaterTimerTest() {}
+  ComponentUpdaterTimerTest()
+      : scoped_task_environment_(
+            base::test::ScopedTaskEnvironment::MainThreadType::UI) {}
   ~ComponentUpdaterTimerTest() override {}
 
  private:
-  base::MessageLoopForUI message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
 };
 
 TEST_F(ComponentUpdaterTimerTest, Start) {