Add an option to create unpremultiplied bitmaps.
Currently they cannot be used directly by Skia, but
the pixels can be used elsewhere.

SkImageDecoder:
Add functions to require unpremultiplied output
and query the presence of the requirement

SkImageDecoder_libpng:
SkImageDecoder_libwebp:
SkImageDecoder_WIC:
Respect the requirement for unpremultiplied output.
TODO: Fix SkImageDecoder_CG.

SkScaledBitmapSampler:
Add procs to skip premultiplication and a boolean
parameter to use those procs.

ImageDecodingTest:
Test unpremultiplied bitmap decoding.

SampleUnpremul:
Add a sample which allows visually comparing between the
unpremultiplied version (copied into a premultiplied bitmap,
since drawing unpremultiplied is not currently supported)
and a premultiplied version of image files.

gm.h:
Add a getter for the resource path, so Samples can use it.

As of patch set 13, https://codereview.chromium.org/16816016/
and https://codereview.chromium.org/16983004/, which were
approved separately.

R=reed@google.com

Review URL: https://codereview.chromium.org/16410009

git-svn-id: http://skia.googlecode.com/svn/trunk@9612 2bbb7eff-a529-9590-31e7-b0007b416f81
15 files changed