GitLab

Pulled the event handler that spies on the root window's event stream
(pre target event handler) into a separate class. Intrinsic
BubbleDialogDelegateView behaviors were marking some events as handled
which prevented them from being passed to the appropriate browser views.

The net result was that drag no longer worked if hover cards were
active; there were probably other problems as well.

Bug: 910739
Change-Id: I747f5ff2ab492367b07ca26a96ea5a5329acb871
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1540681
Commit-Queue: Dana Fried <dfried@chromium.org>
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644652}