Add the ability to provide function pointers to SkPicture serialization
and deserialization for encoding and decoding bitmaps.

Remove kForceFlattenBitmapPixels_Flag, which is no longer used.

When an SkOrderedReadBuffer needs to read a bitmap, if it does not
have an image decoder, use a dummy bitmap.

In GM, add a tolerance option for color differences, used when
testing picture serialization, so it can assume two images are the
same even though PNG encoding/decoding may have resulted in small
differences.

Create dummy implementations for SkImageDecoder and SkImageEncoder
functions in SkImageDecoder_empty so that a project that does not
want to include the images project it can still build.

Allow ports to build without images project.

In Mac's image encoder, copy 4444 to 8888 before encoding.

Add SkWriter32::reservePad, to provide a pointer to write non 4 byte
aligned data, padded with zeroes.

In bench_ and render_ pictures, pass decode function to SkPicture
creation from a stream.

BUG=https://code.google.com/p/skia/issues/detail?id=842

Review URL: https://codereview.appspot.com/6551071

git-svn-id: http://skia.googlecode.com/svn/trunk@5818 2bbb7eff-a529-9590-31e7-b0007b416f81
21 files changed