Remove bitmap reuse from SkImageDecoder.

Now that Android is using an SkBitmap::Allocator to reuse bitmap
memory, remove the unnecessary code to handle bitmap reuse inside
the decoders themselves.

Leaves in the code for bitmap reuse in decodeSubset, which still
may reuse bitmaps, and cropBitmap, which is called by decodeSubset.

R=djsollen@google.com

Review URL: https://codereview.chromium.org/17620004

git-svn-id: http://skia.googlecode.com/svn/trunk@9931 2bbb7eff-a529-9590-31e7-b0007b416f81
10 files changed