Draft CL at https://chromium-review.googlesource.com/c/567266/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7c9efb2c74e9e20e4c4c23eafdeff07da09b4745

commit 7c9efb2c74e9e20e4c4c23eafdeff07da09b4745
Author: Valery Arkhangorodsky <varkha@chromium.org>
Date: Thu Jul 13 20:08:06 2017

Makes it easier to resize transient children of top level windows

Extends the use of EasyResizeWindowTargeter to transient children of
top level windows that currently use EasyResizeWindowTargeter - as long
as those children can themselves be resized.

Bug:  741013 
Test: added ToplevelWindowEventHandlerTest.EasyResizerUsed
Change-Id: I5e9db48e80210a0ee108dcbd8f02dd33b1c62d78
Reviewed-on: https://chromium-review.googlesource.com/567266
Commit-Queue: Valery Arkhangorodsky <varkha@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486466}
[modify] https://crrev.com/7c9efb2c74e9e20e4c4c23eafdeff07da09b4745/ash/wm/toplevel_window_event_handler_unittest.cc
[modify] https://crrev.com/7c9efb2c74e9e20e4c4c23eafdeff07da09b4745/ash/wm/window_modality_controller_unittest.cc
[modify] https://crrev.com/7c9efb2c74e9e20e4c4c23eafdeff07da09b4745/ui/wm/core/easy_resize_window_targeter.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7ef93f21228707615273c62c966d082bacc67479

commit 7ef93f21228707615273c62c966d082bacc67479
Author: Valery Arkhangorodsky <varkha@chromium.org>
Date: Fri Jul 21 01:57:25 2017

Makes non-resizable windows not use EasyResizeWindowTargeter

This was suggested in https://chromium-review.googlesource.com/c/567266/
Make EasyResizeWindowTargeter only extend hit-test region of resizable
windows.
Make exception for the shelf container that uses expanded hit-test
despite the shelf widget being not resizable (this helps with dragging
the shelf when it is auto-hidden).

      Modified ShapedAppWindowTargeterTest.HitTestOnlyForShapedWindow
  Open music.google.com
  Use a mini-player (accessible with a pop-out button next to playback controls)
  Position mini-player next to some other touchable control from a window directly
    below (e.g. Chrome menu or bookmark bar)
  Tap outside of the mini-player but close to it
  The tap should go to the window below.
  

Bug:  741013 
Test: Added ToplevelWindowEventHandlerTest.EasyResizerUsedForTopLevel
Test: Manual:
Change-Id: I6bc6abb603689562eeb498e3741540f4ed3d75e0
Reviewed-on: https://chromium-review.googlesource.com/571953
Commit-Queue: Valery Arkhangorodsky <varkha@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488547}
[modify] https://crrev.com/7ef93f21228707615273c62c966d082bacc67479/ash/shelf/shelf_window_targeter.cc
[modify] https://crrev.com/7ef93f21228707615273c62c966d082bacc67479/ash/shelf/shelf_window_targeter.h
[modify] https://crrev.com/7ef93f21228707615273c62c966d082bacc67479/ash/wm/toplevel_window_event_handler_unittest.cc
[modify] https://crrev.com/7ef93f21228707615273c62c966d082bacc67479/chrome/browser/ui/views/apps/shaped_app_window_targeter_unittest.cc
[modify] https://crrev.com/7ef93f21228707615273c62c966d082bacc67479/ui/wm/core/easy_resize_window_targeter.cc
[modify] https://crrev.com/7ef93f21228707615273c62c966d082bacc67479/ui/wm/core/easy_resize_window_targeter.h