Fixes for factory GM.

Fixes for factory GM.

Skip cross process pipe playback in gm/factory.cpp. Add a new flag to
gm.h to skip only this form of pipe playback.

In gmmain.cpp, use a bitmap encoder function for serialization that
stores the encoded data if present, and use a bitmap decoder on
deserialization. This allows gm/factory to work through serialization.
Also respect the new pipe skipping flag.

BUG=https://code.google.com/p/skia/issues/detail?id=1231

Committed: http://code.google.com/p/skia/source/detail?r=10786

[borenet, 2013-08-16 19:07:12]

This LGTM but I'm not at all familiar with what this code does or why it's
needed.

[commit-bot: I haz the power, 2013-08-16 19:10:54]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/scroggo@google.com/23192004/3001

[commit-bot: I haz the power, 2013-08-16 19:18:18]

Change committed as 10786