ObjPtr<>-ify mirror::ObjectArray.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 31113334
Change-Id: I611b3e49d3feed306f6cd35d2b662a1e727e24c6
diff --git a/runtime/debugger.cc b/runtime/debugger.cc
index 9c9fdbb..26ae38a 100644
--- a/runtime/debugger.cc
+++ b/runtime/debugger.cc
@@ -527,7 +527,7 @@
  *
  * Null objects are tagged JT_OBJECT.
  */
-JDWP::JdwpTag Dbg::TagFromObject(const ScopedObjectAccessUnchecked& soa, mirror::Object* o) {
+JDWP::JdwpTag Dbg::TagFromObject(const ScopedObjectAccessUnchecked& soa, ObjPtr<mirror::Object> o) {
   return (o == nullptr) ? JDWP::JT_OBJECT : TagFromClass(soa, o->GetClass());
 }
 
@@ -1277,7 +1277,7 @@
     ScopedObjectAccessUnchecked soa(Thread::Current());
     mirror::ObjectArray<mirror::Object>* oa = a->AsObjectArray<mirror::Object>();
     for (int i = 0; i < count; ++i) {
-      mirror::Object* element = oa->Get(offset + i);
+      ObjPtr<mirror::Object> element = oa->Get(offset + i);
       JDWP::JdwpTag specific_tag = (element != nullptr) ? TagFromObject(soa, element)
                                                         : element_tag;
       expandBufAdd1(pReply, specific_tag);