sync-and-gyp

sync-and-gyp is a Python program that wraps gclient sync and gyp_skia. Motivations for using it:

Fewer steps to configure and compile Skia and Skia's dependencies. This makes documentation cleaner, too.
Written in Python, so it will work on all platforms. Python is already necessary for gyp.
Sets up gclient better than gclient config, which has been broken.
Checks to see if the DEPS file has changed since it last ran gclient sync. If not, it skips that step.
Checks to see if gyp needs to be re-run (it checks environment variables and changed or added files); if not, it skips running gyp_skia.
Since running sync-and-gyp is fast when it can do nothing, it is easy to do before every recompile of Skia. This is a good habit.