WorkspaceControllerTest.WindowEdgeMouseHitTestPanel starts failing only in mash when the shelf is moved to LockScreenRelatedContainers (instead of NonLockScreenContianers) because event targeting is focusing the shelf instead of the panel. This only happens when a ShelfButton instance is created

https://chromium-review.googlesource.com/c/chromium/src/+/726240 is the CL that introduces the regression, because flipping views-lock on by default moves the shelf container.

The test is verifying that events outside of the panel get redirected to the panel. Only the event below the panel is redirected to the shelf.