Move mirror::Object setters to ObjPtr

Bug: 31113334

Test: test-art-host

Change-Id: I2c4c84645e194c3c435a4a6fd670176b0e98671f
diff --git a/runtime/gc/heap.h b/runtime/gc/heap.h
index e32f057..678edff 100644
--- a/runtime/gc/heap.h
+++ b/runtime/gc/heap.h
@@ -438,11 +438,10 @@
 
   // Must be called if a field of an Object in the heap changes, and before any GC safe-point.
   // The call is not needed if null is stored in the field.
-  ALWAYS_INLINE void WriteBarrierField(const mirror::Object* dst,
-                                       MemberOffset offset ATTRIBUTE_UNUSED,
-                                       const mirror::Object* new_value ATTRIBUTE_UNUSED) {
-    card_table_->MarkCard(dst);
-  }
+  ALWAYS_INLINE void WriteBarrierField(ObjPtr<mirror::Object> dst,
+                                       MemberOffset offset,
+                                       ObjPtr<mirror::Object> new_value)
+      REQUIRES_SHARED(Locks::mutator_lock_);
 
   // Write barrier for array operations that update many field positions
   ALWAYS_INLINE void WriteBarrierArray(const mirror::Object* dst,