Include the AppData file for Chrome and Chromium

Add the two AppData files, one for Chromium and one for Chrome. The Chrome one
will be filled with the information from the common/google-chrome/google-chrome.info
file and should reflect the current channel (stable, beta, devel). On the other
side the Chromium one should be a general one and it will be reused by
distributions that are packaging the Chromium themselves.

For AppData specification please see:
https://people.freedesktop.org/~hughsient/appdata/

BUG=654190

Review-Url: https://codereview.chromium.org/2424093003
Cr-Original-Commit-Position: refs/heads/master@{#455457}
Committed: https://chromium.googlesource.com/chromium/src/+/d6807b9a7da70dae9191b93d4ec6157187515078
Review-Url: https://codereview.chromium.org/2424093003
Cr-Commit-Position: refs/heads/master@{#455731}
5 files changed