Revert "Do not return Index8 from SkAndroidCodec::computeOutputColorType"

This reverts commit b6f4767294261dca3beef6f280c4bac69df3f930.

Reason for revert: This breaks CTS tests in Android.  Doh.

Original change's description:
> Do not return Index8 from SkAndroidCodec::computeOutputColorType
> 
> Given that this is the only known use of Index8 color type,
> this is essentially an experimental delete.
> 
> Bug: skia:6620
> Change-Id: Ib363d237e0217f6e7f461a62e54d32892c428095
> Reviewed-on: https://skia-review.googlesource.com/10586
> Reviewed-by: Leon Scroggins <scroggo@google.com>
> Commit-Queue: Matt Sarett <msarett@google.com>

TBR=msarett@google.com,scroggo@google.com,reed@google.com
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:6620

Change-Id: I2b44c695b8b95659520e9532901f636f56e01e2a
Reviewed-on: https://skia-review.googlesource.com/19084
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>
2 files changed