Parse imageMediaMetadata field from Drive API.

This patch adds parsers for the image media related fields: width, height and rotation of the image. These fields are available in Drive API, but not in WAPI. This is not a big problem, since WAPI is used only for fast fetch. Therefore, these fields may not be available before the full fetch.

TEST=browser_tests
BUG=170309
R=benwells@chromium.org, kinaba@chromium.org, yoshiki@chromium.org

Review URL: https://codereview.chromium.org/25827002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226973 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226973