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/entrypoints/quick/quick_field_entrypoints.cc b/runtime/entrypoints/quick/quick_field_entrypoints.cc
index 70eb1de..6d17000 100644
--- a/runtime/entrypoints/quick/quick_field_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_field_entrypoints.cc
@@ -151,14 +151,14 @@
                                   StaticObjectRead,
                                   sizeof(mirror::HeapReference<mirror::Object>));
   if (LIKELY(field != nullptr)) {
-    return field->GetObj(field->GetDeclaringClass()).Decode();
+    return field->GetObj(field->GetDeclaringClass()).Ptr();
   }
   field = FindFieldFromCode<StaticObjectRead, true>(field_idx,
                                                     referrer,
                                                     self,
                                                     sizeof(mirror::HeapReference<mirror::Object>));
   if (LIKELY(field != nullptr)) {
-    return field->GetObj(field->GetDeclaringClass()).Decode();
+    return field->GetObj(field->GetDeclaringClass()).Ptr();
   }
   return nullptr;  // Will throw exception by checking with Thread::Current.
 }
@@ -299,7 +299,7 @@
                                   InstanceObjectRead,
                                   sizeof(mirror::HeapReference<mirror::Object>));
   if (LIKELY(field != nullptr && obj != nullptr)) {
-    return field->GetObj(obj).Decode();
+    return field->GetObj(obj).Ptr();
   }
   field = FindInstanceField<InstanceObjectRead, true>(field_idx,
                                                       referrer,
@@ -307,7 +307,7 @@
                                                       sizeof(mirror::HeapReference<mirror::Object>),
                                                       &obj);
   if (LIKELY(field != nullptr)) {
-    return field->GetObj(obj).Decode();
+    return field->GetObj(obj).Ptr();
   }
   return nullptr;  // Will throw exception by checking with Thread::Current.
 }