Misc. small changes in preparation for moving popup mode edge drawing.

* Comment/variable name changes for clarity.
* Remove code to paint toolbar top separator for glass when the toolbar is invisible.  AFAICT this never has a visible effect.
* Modify how opaque frames layout popups so the responsibility to reserve extra space lies with OpaqueBrowserFrameViewLayout, not ToolbarView.
* Pass width/height instead of right/bottom to OpaqueBrowserFrameView::FillClientEdgeRects(), which will make it a bit easier to call this from another place in the future.
* Move static const declaration to match style guide.
* Declare the location bar border color as a file-scope constant in preparation for using it in more places.

BUG=none
TEST=none
R=sky@chromium.org

Review URL: https://codereview.chromium.org/1682373002 .

Cr-Commit-Position: refs/heads/master@{#375151}
10 files changed