Swap default_image from .png to .xml drawable

Save a few hundred KB in the APK

cherry-pick of: https://googleplex-android-review.googlesource.com/#/c/283490/

Change-Id: If212ac4af30f5a98f354ebd0820902269544f4ca
2 files changed
tree: 11a4aa756574901f22a0dc0e17fd0c4d647e1019
  1. res/
  2. sample/
  3. src/
  4. .gitignore
  5. Android.mk
  6. AndroidManifest.xml