Reland "Allow dragging for NonClientArea (i.e. DraggableRegions)"

The non-client area in ProxyWindow is set through "DraggableRegions",
and this section is used for draggability of the window (see

The same logic should be introduced on Mash, otherwise frameless
app window can't be dragged.

The previous CL (r622061) was reverted since this CL actually
makes any browser-windows unresizable -- this draggable-regions
check should be done only when the located event isn't on the
edge (i.e. keep the existing behavior as long as it returns
values other than HTCLIENT).

Bug: 920469
Test: ash_unittests
Change-Id: I9389e35ae8cb89b84df6517e932acaa5cb7ebaa7
Reviewed-by: Scott Violet <>
Commit-Queue: Jun Mukai <>
Cr-Commit-Position: refs/heads/master@{#622239}
6 files changed