GitLab

support upscaling directly in png codec to preferred config
remove copyTo post-upscaling in base imagedecoder, since that breaks our Allocator model for custom
allocators (like ashmem), which can't be called twice on two different configs.

check if we can promote to the preferred config

the width and height infomation from the header directly.

respect preferred config for index-based pngs

255, i.e., no need to add previous destination color values.

My experimental results showed that the percentage of calls
to SkSrcOver32To16() falling into the bypass path in the following
processes are around:
1. system_server: 72%
2. acore: 80%
3. camera: 57%
4. browser: 66%

This was originally done by Mike. I'll ask him to review this.