Implement getters for app window bounds API
This is the first patch for the new app window bounds API.
- The current Bounds class was renamed ContentBounds in order to
introduce a different Bounds class for the new API
- The properties of the innerBounds and outerBounds can now be read
- Some already deprecated bounds fields in CreateWindowOptions are no
longer documented
BUG=315471
Review URL: https://codereview.chromium.org/
179393002
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253729 0039d316-1c4b-4281-b951-d872f2087c98