Currently we use gsutil to download ndk. However, it requires extra
steps to install, and is not convenient to configure (several steps to
enable Google storage), especially for developers behind proxy (need to
set config of boto). Chromium provides some python scripts to help
download nacl toolchains that can meet this need well. So this patch
basically borrows two python scripts from there, and makes some
according changes to remove the usage of gsutil. With new script, we may
also implement some advanced features, such as hash check, so that the
download would be more intelligent.
BUG=
R=djsollen@google.com, borenet@google.com, reed@google.com
Author: yang.gu@intel.com
Review URL: https://chromiumcodereview.appspot.com/15951008
git-svn-id: http://skia.googlecode.com/svn/trunk@9311 2bbb7eff-a529-9590-31e7-b0007b416f81
