Move most mirror:: args to ObjPtr

Fixed possible moving GC bugs in ClinitImageUpdate class.

Bug: 31113334

Test: test-art-host
Change-Id: I0bf6578553d58b944aaa17665f1350bdf5ed15ec
diff --git a/runtime/mirror/field.cc b/runtime/mirror/field.cc
index 65f6b16..f6b6489 100644
--- a/runtime/mirror/field.cc
+++ b/runtime/mirror/field.cc
@@ -27,7 +27,7 @@
 GcRoot<Class> Field::static_class_;
 GcRoot<Class> Field::array_class_;
 
-void Field::SetClass(Class* klass) {
+void Field::SetClass(ObjPtr<Class> klass) {
   CHECK(static_class_.IsNull()) << static_class_.Read() << " " << klass;
   CHECK(klass != nullptr);
   static_class_ = GcRoot<Class>(klass);
@@ -38,7 +38,7 @@
   static_class_ = GcRoot<Class>(nullptr);
 }
 
-void Field::SetArrayClass(Class* klass) {
+void Field::SetArrayClass(ObjPtr<Class> klass) {
   CHECK(array_class_.IsNull()) << array_class_.Read() << " " << klass;
   CHECK(klass != nullptr);
   array_class_ = GcRoot<Class>(klass);