Add an SkImageGenerator that uses NDK APIs

Bug: skia:10369
Bug: skia:10371

This will allow Skia clients developing for Android 11+ to rely on
Android's NDK APIs for decoding, which will allow them to decode
without including their own decoding libraries (e.g. libjpeg-turbo).
Using these APIs also provides support for static HEIF images.

Run ImageGenSrc in kPlatform_Mode on Android to verify decoding

Add tests and a grayscale png.

Update some test bots running Android R to specify ndk_api so they will
run the new code.

Change-Id: Ica782339b2414d472ede0b61729a127ce41892a5
Reviewed-by: Mike Klein <>
Commit-Queue: Leon Scroggins <>
12 files changed