Rename ObjPtr::Decode to ObjPtr::Ptr

Done to prevent ambiguity with ScopedObjectAccess::Decode.

Bug: 31113334

Test: test-art-host
Change-Id: I07a2497cc9cf66386311798933547471987fc316
diff --git a/runtime/mirror/class-inl.h b/runtime/mirror/class-inl.h
index 3cbd58b..1cfed74 100644
--- a/runtime/mirror/class-inl.h
+++ b/runtime/mirror/class-inl.h
@@ -384,7 +384,7 @@
     DCHECK(dex_access_to != nullptr);
     if (UNLIKELY(!this->CanAccess(dex_access_to))) {
       if (throw_on_failure) {
-        ThrowIllegalAccessErrorClass(this, dex_access_to.Decode());
+        ThrowIllegalAccessErrorClass(this, dex_access_to.Ptr());
       }
       return false;
     }
@@ -422,7 +422,7 @@
     if (UNLIKELY(!this->CanAccess(dex_access_to))) {
       if (throw_on_failure) {
         ThrowIllegalAccessErrorClassForMethodDispatch(this,
-                                                      dex_access_to.Decode(),
+                                                      dex_access_to.Ptr(),
                                                       method,
                                                       throw_invoke_type);
       }
@@ -448,7 +448,7 @@
 inline bool Class::CheckResolvedFieldAccess(ObjPtr<Class> access_to,
                                             ArtField* field,
                                             uint32_t field_idx) {
-  return ResolvedFieldAccessTest<true, true>(access_to.Decode(), field, field_idx, nullptr);
+  return ResolvedFieldAccessTest<true, true>(access_to.Ptr(), field, field_idx, nullptr);
 }
 
 inline bool Class::CanAccessResolvedMethod(Class* access_to, ArtMethod* method,