ART: Add dex::StringIndex

Add abstraction for uint32_t string index.

Test: m test-art-host
Change-Id: I917c2881702fe3df112c713f06980f2278ced7ed
diff --git a/runtime/native/java_lang_DexCache.cc b/runtime/native/java_lang_DexCache.cc
index f6de593..f1c350f 100644
--- a/runtime/native/java_lang_DexCache.cc
+++ b/runtime/native/java_lang_DexCache.cc
@@ -61,7 +61,8 @@
   ScopedFastNativeObjectAccess soa(env);
   ObjPtr<mirror::DexCache> dex_cache = soa.Decode<mirror::DexCache>(javaDexCache);
   CHECK_LT(static_cast<size_t>(string_index), dex_cache->GetDexFile()->NumStringIds());
-  return soa.AddLocalReference<jobject>(dex_cache->GetResolvedString(string_index));
+  return soa.AddLocalReference<jobject>(
+      dex_cache->GetResolvedString(dex::StringIndex(string_index)));
 }
 
 static void DexCache_setResolvedType(JNIEnv* env, jobject javaDexCache, jint type_index,
@@ -77,7 +78,7 @@
   ScopedFastNativeObjectAccess soa(env);
   ObjPtr<mirror::DexCache> dex_cache = soa.Decode<mirror::DexCache>(javaDexCache);
   CHECK_LT(static_cast<size_t>(string_index), dex_cache->GetDexFile()->NumStringIds());
-  dex_cache->SetResolvedString(string_index, soa.Decode<mirror::String>(string));
+  dex_cache->SetResolvedString(dex::StringIndex(string_index), soa.Decode<mirror::String>(string));
 }
 
 static JNINativeMethod gMethods[] = {