Refactor app_login out of ChromeOS

Xiyuan created an app login webUI based on gaia auth extension for identity signin flow in ChromeOS. This CL refactors that code out of ChromeOS package so that Chrome desktop could reuse the code for similar inline signin flows, such as sign in from launcher/wallet.

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Review URL: https://codereview.chromium.org/15014013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@200256 0039d316-1c4b-4281-b951-d872f2087c98
24 files changed