Implement MD specs for non-tabbed windows in Ash

For material design in Ash, non-tabbed windows
draw a 1px (regardless of device scale factor)
separator line drawn between the frame header,
location bar (if one is visible), and the window
contents. Furthermore, remove extra vertical
spacing between these elements so that no toolbar
theming is visible.

BUG=580302,585856
TEST=manual, BrowserTest.TestPopupBounds

Review URL: https://codereview.chromium.org/1636703002

Cr-Commit-Position: refs/heads/master@{#374923}
4 files changed