The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4545062c75118e1a633987878b524277f33c9bbc

commit 4545062c75118e1a633987878b524277f33c9bbc
Author: jamescook <jamescook@chromium.org>
Date: Tue Aug 02 18:48:01 2016

mash: Migrate ScopedTargetRootWindow to //ash/common

It's a dependency of ShelfView, which we're trying to move.

* Rename to ScopedRootWindowForNewWindows, the more-descriptive name we're
using in mus code.
* Move ownership of root_window_for_new_windows_ to WmShell.
* ash::Shell no longer needs to be an activation observer, since it was only
using that to set the target root window, and we can do that in WmShellAura
now.
* Fix some tests that were unnecessarily setting the target root window to
the primary display, which is the default.

BUG= 633323 
TEST=ash_unittests, unit_tests, create new browser windows by clicking on the
browser shortcut shelf item on different displays

Review-Url: https://codereview.chromium.org/2194353002
Cr-Commit-Position: refs/heads/master@{#409256}

[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/ash.gyp
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/aura/wm_shell_aura.cc
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/aura/wm_shell_aura.h
[add] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/common/scoped_root_window_for_new_windows.cc
[add] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/common/scoped_root_window_for_new_windows.h
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/common/wm_shell.cc
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/common/wm_shell.h
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/display/screen_position_controller.cc
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/drag_drop/drag_drop_tracker_unittest.cc
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/mus/bridge/wm_shell_mus.cc
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/mus/bridge/wm_shell_mus.h
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/root_window_controller.cc
[delete] https://crrev.com/7db633ed3af213c5220d188fb9caf4b1e1973692/ash/scoped_target_root_window.cc
[delete] https://crrev.com/7db633ed3af213c5220d188fb9caf4b1e1973692/ash/scoped_target_root_window.h
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/shelf/shelf_view.cc
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/shelf/shelf_view.h
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/shell.cc
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/shell.h
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/wm/window_cycle_controller_unittest.cc
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/ash/wm/window_positioner_unittest.cc
[modify] https://crrev.com/4545062c75118e1a633987878b524277f33c9bbc/chrome/browser/ui/window_sizer/window_sizer_ash_unittest.cc