Remove SkBitmap from ResourceCache

Bug: 18928352

Fully-proper refcounting via SkBitmap/SkPixelRef, no more
side-channel refcounting via ResourceCache. Makes HWUI
more resilient to the bitmap being modified as well as
the SkBitmap's info & rowBytes() is updated every time
a DisplayList is recorded instead of relying on buggy
cache eviction logic

Change-Id: I2e8292d62ab6c257a2cfa1542387bf2bf1ade816