Add command line flag for disabling some Ash-specific logic for
arranging new Browser windows.

This also reinstates some logic for Mash that doesn't depend on code
in ash/. With this flag passed, or when running in Mash,
ash::WindowPositioner won't be used for placing new Windows. Some
other Chrome OS specific code, like maximizing the first run window
according to policy, is retained.

Bug: 764009
Change-Id: I7563b0b0648e2470ec4a601805d2b351b6d64bb0
Reviewed-on: https://chromium-review.googlesource.com/958030
Commit-Queue: Evan Stade <[email protected]>
Reviewed-by: Scott Violet <[email protected]>
Reviewed-by: James Cook <[email protected]>
Cr-Commit-Position: refs/heads/master@{#542858}
7 files changed