Add buffer helper to read directly into SkString to avoid extra copying

src/core/SkPaintOptionsAndroid.cpp

 
 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifdef SK_BUILD_FOR_ANDROID
 
@@ skipping 16 matching lines @@
     return SkLanguage(tag, parentTagLen);
 }
 
 void SkPaintOptionsAndroid::flatten(SkFlattenableWriteBuffer& buffer) const {
     buffer.writeUInt(fFontVariant);
     buffer.writeString(fLanguage.getTag().c_str());
 }
 
 void SkPaintOptionsAndroid::unflatten(SkFlattenableReadBuffer& buffer) {
     fFontVariant = (FontVariant)buffer.readUInt();
-    char* tag = buffer.readString();
+    SkString tag;
+    buffer.readString(tag);
     fLanguage = SkLanguage(tag);
-    sk_free(tag);
 }
 
 #endif