Use ScopedTaskEnvironment instead of MessageLoopForUI in chrome tests.

chrome/browser/chromeos/settings/install_attributes_unittest.cc

Index: chrome/browser/chromeos/settings/install_attributes_unittest.cc
diff --git a/chrome/browser/chromeos/settings/install_attributes_unittest.cc b/chrome/browser/chromeos/settings/install_attributes_unittest.cc
index 9b61b32fe16a3c4b2d5c1e1fd0f90a8e15027303..cf992f45241b5e12f3f0606c57206b7925920ba8 100644
--- a/chrome/browser/chromeos/settings/install_attributes_unittest.cc
+++ b/chrome/browser/chromeos/settings/install_attributes_unittest.cc
@@ -13,6 +13,7 @@
 #include "base/memory/ptr_util.h"
 #include "base/path_service.h"
 #include "base/run_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "chrome/browser/chromeos/policy/proto/install_attributes.pb.h"
 #include "chromeos/chromeos_paths.h"
 #include "chromeos/cryptohome/cryptohome_util.h"
@@ -48,7 +49,9 @@ static const char kTestUserDeprecated[] = "test@example.com";
 
 class InstallAttributesTest : public testing::Test {
  protected:
-  InstallAttributesTest() {}
+  InstallAttributesTest()
+      : scoped_task_environment_(
+            base::test::ScopedTaskEnvironment::MainThreadType::UI) {}
 
   void SetUp() override {
     ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
@@ -76,7 +79,7 @@ class InstallAttributesTest : public testing::Test {
     attribute->set_value(value);
   }
 
-  base::MessageLoopForUI message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
   base::ScopedTempDir temp_dir_;
   std::unique_ptr<InstallAttributes> install_attributes_;