I'll take a look

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5a98d6119a8d9499f6d64b8b80428ae3e48708ee

commit 5a98d6119a8d9499f6d64b8b80428ae3e48708ee
Author: Jun Mukai <mukai@chromium.org>
Date: Fri Jan 11 18:21:33 2019

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
https://cs.chromium.org/chromium/src/apps/ui/views/app_window_frame_view.cc?sq=package:chromium&g=0&l=196).

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

Bug:  920469 
Test: ash_unittests
Change-Id: If249d58dbf0a84aa3b333799f44f122dca04c4e6
Reviewed-on: https://chromium-review.googlesource.com/c/1405458
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622061}
[modify] https://crrev.com/5a98d6119a8d9499f6d64b8b80428ae3e48708ee/ash/wm/non_client_frame_controller.cc
[modify] https://crrev.com/5a98d6119a8d9499f6d64b8b80428ae3e48708ee/ash/wm/non_client_frame_controller_unittest.cc
[modify] https://crrev.com/5a98d6119a8d9499f6d64b8b80428ae3e48708ee/services/ws/BUILD.gn
[modify] https://crrev.com/5a98d6119a8d9499f6d64b8b80428ae3e48708ee/services/ws/proxy_window.cc
[add] https://crrev.com/5a98d6119a8d9499f6d64b8b80428ae3e48708ee/services/ws/window_utils.cc
[add] https://crrev.com/5a98d6119a8d9499f6d64b8b80428ae3e48708ee/services/ws/window_utils.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/045eddcd250fbc7622da5dff12bdfb083a27e947

commit 045eddcd250fbc7622da5dff12bdfb083a27e947
Author: Jun Mukai <mukai@chromium.org>
Date: Fri Jan 11 22:29:44 2019

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

This reverts commit 5a98d6119a8d9499f6d64b8b80428ae3e48708ee.

Reason for revert: browser-windows get unresizable

Original change's description:
> 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
> https://cs.chromium.org/chromium/src/apps/ui/views/app_window_frame_view.cc?sq=package:chromium&g=0&l=196).
> 
> The same logic should be introduced on Mash, otherwise frameless
> app window can't be dragged.
> 
> Bug:  920469 
> Test: ash_unittests
> Change-Id: If249d58dbf0a84aa3b333799f44f122dca04c4e6
> Reviewed-on: https://chromium-review.googlesource.com/c/1405458
> Reviewed-by: Scott Violet <sky@chromium.org>
> Commit-Queue: Jun Mukai <mukai@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#622061}

TBR=mukai@chromium.org,sky@chromium.org

Change-Id: Ib51b583478e4d74c5754d0c243708bcd6a368d66
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  920469 
Reviewed-on: https://chromium-review.googlesource.com/c/1407666
Reviewed-by: Jun Mukai <mukai@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622189}
[modify] https://crrev.com/045eddcd250fbc7622da5dff12bdfb083a27e947/ash/wm/non_client_frame_controller.cc
[modify] https://crrev.com/045eddcd250fbc7622da5dff12bdfb083a27e947/ash/wm/non_client_frame_controller_unittest.cc
[modify] https://crrev.com/045eddcd250fbc7622da5dff12bdfb083a27e947/services/ws/BUILD.gn
[modify] https://crrev.com/045eddcd250fbc7622da5dff12bdfb083a27e947/services/ws/proxy_window.cc
[delete] https://crrev.com/ee6cf5ee2c5c989c34d0a4ca16e1ba314c6596b4/services/ws/window_utils.cc
[delete] https://crrev.com/ee6cf5ee2c5c989c34d0a4ca16e1ba314c6596b4/services/ws/window_utils.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6052a653c5e5b430ee4f3ba9e41b37b4f78752d6

commit 6052a653c5e5b430ee4f3ba9e41b37b4f78752d6
Author: Jun Mukai <mukai@chromium.org>
Date: Sat Jan 12 00:44:33 2019

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
https://cs.chromium.org/chromium/src/apps/ui/views/app_window_frame_view.cc?sq=package:chromium&g=0&l=196).

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-on: https://chromium-review.googlesource.com/c/1407776
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622239}
[modify] https://crrev.com/6052a653c5e5b430ee4f3ba9e41b37b4f78752d6/ash/wm/non_client_frame_controller.cc
[modify] https://crrev.com/6052a653c5e5b430ee4f3ba9e41b37b4f78752d6/ash/wm/non_client_frame_controller_unittest.cc
[modify] https://crrev.com/6052a653c5e5b430ee4f3ba9e41b37b4f78752d6/services/ws/BUILD.gn
[modify] https://crrev.com/6052a653c5e5b430ee4f3ba9e41b37b4f78752d6/services/ws/proxy_window.cc
[add] https://crrev.com/6052a653c5e5b430ee4f3ba9e41b37b4f78752d6/services/ws/window_utils.cc
[add] https://crrev.com/6052a653c5e5b430ee4f3ba9e41b37b4f78752d6/services/ws/window_utils.h