Fixes for JPEG subset decoding.

Ensure that the stream passed to JPEG for subset decoding is
neither deleted before it is no longer needed nor deleted an
extra time.

src/images/SkJpegUtility.h:
src/images/SkJpegUtility.cpp:
Always ref and unref the stream provided to skjpeg_source_mgr.
Add some comments explaining how skjpeg_source_mgr's members
handle ownership.
Fix a warning comparing signed and unsigned numbers, converting
to size_t which is more appropriate for measuring bytes.
Remove dead code referring to fMemoryBase and fMemoryBaseSize,
which are never used.

src/images/SkImageDecoder_libjpeg.cpp:
Call the new constructor for skjpeg_source_mgr, which no longer
takes a boolean to determine ownership.

include/images/SkBitmapRegionDecoder.h
src/images/SkBitmapRegionDecoder.cpp:
This small shim has been removed, since it is not needed to use
Skia's image decoders. Its functionality will be folded into
Android.

Required for the merge to Android.

R=djsollen@google.com

Review URL: https://codereview.chromium.org/21561002

git-svn-id: http://skia.googlecode.com/svn/trunk@10483 2bbb7eff-a529-9590-31e7-b0007b416f81
6 files changed