Store ninepatch chunks in the png header in CodexTest

We are making a change in Android to store ninepatch chunks in the
png header.  Thus, our ninepatch test should match the Android
framework's use.
https://googleplex-android-review.git.corp.google.com/#/c/832067/

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1553303003

Review URL: https://codereview.chromium.org/1553303003
2 files changed