Mojo: Move a bunch of bindings "library" stuff to pylib subdirectory.

Still to do: Stuff in the generators directory, which will be split in a
different (and more complicated) way.

Originally landed: r246807
Reverted: r246816 (due to lack of android webview whitelist update)

R=darin@chromium.org
TBR=boliu@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=

Review URL: https://codereview.chromium.org/146163002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246920 0039d316-1c4b-4281-b951-d872f2087c98
content-shell: Allow running content-shell headless with --dump-render-tree.

Do some refactoring to allow using ShellAuraPlatformData in aura content_shell
(with or without views). ShellAuraPlatformData is used for non-views aura
content_shell (e.g. ozone) for all purposes, and in views content_shell only for
headless mode.

BUG=316712
R=jam@chromium.org, sky@chromium.org

Review URL: https://codereview.chromium.org/145253002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246921 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246921