namespace_browser: Progressbar needs to be above shadow but below sidebar.
namespace_browser: Progressbar needs to be above shadow but
below sidebar.

https://github.com/veyron/release-issues/issues/779

Change-Id: I7a487aa9b39e00aa855253ffd830c3479d0ae620

vanadium/browser,vanadium/browser,vanadium/browser,vanadium/browser