Android Chromoting: Remove unused permissions
Android Chromoting: Remove unused permissions

The MANAGE_ACCOUNTS and USE_CREDENTIALS
permissions are no longer needed (and are
removed in API level 23).
The app can still request adding/removing
accounts (via the Google account-switcher)
but it does this by firing system Intents,
so the app itself doesn't need the permission.

And the app uses GoogleAuthUtil and doesn't
call the deprecated invalidateToken() method
that requires these permissions.

BUG=546378

Review URL: https://codereview.chromium.org/1523473002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#365288}

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