The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4d3588cbec47fcd629c038a0ca6aad9af58e4192

commit 4d3588cbec47fcd629c038a0ca6aad9af58e4192
Author: sadrul <sadrul@chromium.org>
Date: Sat Jun 25 08:04:16 2016

mus: Allow embedder to intercept events.

Introduce mechanism so that an embedder receives the events targeted to
embedded window. This allows the browser window to receive events, even
when the renderer-content lives in a separate mus::Window.

BUG= 621078 

Review-Url: https://codereview.chromium.org/2068093002
Cr-Commit-Position: refs/heads/master@{#402057}

[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/public/cpp/lib/window.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/public/cpp/lib/window_tree_client.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/public/cpp/tests/test_window_tree.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/public/cpp/tests/test_window_tree.h
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/public/cpp/window.h
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/public/cpp/window_tree_client.h
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/public/interfaces/window_tree.mojom
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/public/interfaces/window_tree_constants.mojom
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/display_binding.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/test_utils.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/test_utils.h
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/window_manager_state.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/window_manager_state_unittest.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/window_server.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/window_server.h
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/window_tree.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/window_tree.h
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/window_tree_client_unittest.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/components/mus/ws/window_tree_unittest.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/content/browser/renderer_host/render_widget_host_view_mus.cc
[modify] https://crrev.com/4d3588cbec47fcd629c038a0ca6aad9af58e4192/content/browser/renderer_host/render_widget_host_view_mus.h

Seems either done or obsolete. Please reopen if I'm wrong.