Lock SkBitmap before accessing color table

This only affects kIndex_8 Bitmaps, which can only be created by
decoding particular images (e.g. GIF). Without locking the SkBitmap,
colorTable() always returns NULL. Lock it so we can write the color
table to the Parcel.

BUG:26527976
Change-Id: Ifc54b06ca08db26ba6455a3830b7e671b64f37c4
1 file changed