De-virtualize SkBitmapController

Fold its only subclass (SkDefaultBitmapController) into base.

Change-Id: I77f5c9f3b459d644d5749b8ec34722ec6c2228bf
Reviewed-on: https://skia-review.googlesource.com/141541
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
4 files changed