Remove DeferredImageDecoder::createResizedLazyDecodingBitmap

Motivation:
    This code is not used.  Removing it will make it easier to make
    changes to Lazy SkPixelRefs in the future.

BUG=

Review URL: https://codereview.chromium.org/71663002

git-svn-id: svn://svn.chromium.org/blink/trunk@161982 bbb929c8-8fbe-4397-9dbb-9b2b20218538