MacViews: Fix CustomFrameViewTest.*Maximized*
The Maximize button on Mac expands the window frame in a
context-specific manner, but never changes window decorations.
This CL gets the following tests passing:
- CustomFrameViewTest.LargerEdgeButtonsWhenMaximized
- CustomFrameViewTest.MaximizeRevealsRestoreButton
On Mac, update expectations to instead check that there is no change to
the custom frame when Widget::Maximize is called.
BUG=378134
TEST=views_unittests
Review URL: https://codereview.chromium.org/
1059533004
Cr-Commit-Position: refs/heads/master@{#324951}