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/test/148-multithread-gc-annotations/gc_coverage.cc b/test/148-multithread-gc-annotations/gc_coverage.cc
index cb12df4..4862b87 100644
--- a/test/148-multithread-gc-annotations/gc_coverage.cc
+++ b/test/148-multithread-gc-annotations/gc_coverage.cc
@@ -35,7 +35,7 @@
 
 extern "C" JNIEXPORT jlong JNICALL Java_MovingGCThread_objectAddress(JNIEnv* env, jclass, jobject object) {
   ScopedObjectAccess soa(env);
-  return reinterpret_cast<jlong>(soa.Decode<mirror::Object>(object).Decode());
+  return reinterpret_cast<jlong>(soa.Decode<mirror::Object>(object).Ptr());
 }
 
 }  // namespace