Clear last MouseMove root view in RWHIER if that view gets destroyed

Clear last MouseMove root view in RWHIER if that view gets destroyed

Cluster-fuzz has reported some difficult-to-reproduce crashes in the
MouseEnter/Leave generation code in RenderWidgetHostInputEventRouter,
and there are some very sparse crash reports appearing for that also.

These might be caused by race conditions from RenderWidgetHostView
tree modifications that get slightly out of sync from the Surface
state that is used for hit testing (Surfaces aren't invalidated until
RWHVs are deleted, which for some RWHVs is not immediate upon them
having Destroy() called).

This CL speculatively tries to address the crashes by having
SendMouseEnterOrLeaveEvents abort when it discovers the RWHV tree out
of sync, and also clearing last_mouse_move_root_view_ when that
gets destroyed.

BUG=647821, 652209
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2396083002
Cr-Commit-Position: refs/heads/master@{#424533}
(cherry picked from commit 83e4f9ac895d5b42a4b114f3ef964676a40476ff)

Committed: https://chromium.googlesource.com/chromium/src/+/68f883645ff0c2f46fa75128af0642e87e7095bd

[kenrb, 2016-11-03 20:59:06]

Description was changed from

==========
Clear last MouseMove root view in RWHIER if that view gets destroyed

Cluster-fuzz has reported some difficult-to-reproduce crashes in the
MouseEnter/Leave generation code in RenderWidgetHostInputEventRouter,
and there are some very sparse crash reports appearing for that also.

These might be caused by race conditions from RenderWidgetHostView
tree modifications that get slightly out of sync from the Surface
state that is used for hit testing (Surfaces aren't invalidated until
RWHVs are deleted, which for some RWHVs is not immediate upon them
having Destroy() called).

This CL speculatively tries to address the crashes by having
SendMouseEnterOrLeaveEvents abort when it discovers the RWHV tree out
of sync, and also clearing last_mouse_move_root_view_ when that
gets destroyed.

BUG=647821, 652209
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2396083002
Cr-Commit-Position: refs/heads/master@{#424533}
(cherry picked from commit 83e4f9ac895d5b42a4b114f3ef964676a40476ff)
==========

to

==========
Clear last MouseMove root view in RWHIER if that view gets destroyed

Cluster-fuzz has reported some difficult-to-reproduce crashes in the
MouseEnter/Leave generation code in RenderWidgetHostInputEventRouter,
and there are some very sparse crash reports appearing for that also.

These might be caused by race conditions from RenderWidgetHostView
tree modifications that get slightly out of sync from the Surface
state that is used for hit testing (Surfaces aren't invalidated until
RWHVs are deleted, which for some RWHVs is not immediate upon them
having Destroy() called).

This CL speculatively tries to address the crashes by having
SendMouseEnterOrLeaveEvents abort when it discovers the RWHV tree out
of sync, and also clearing last_mouse_move_root_view_ when that
gets destroyed.

BUG=647821, 652209
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2396083002
Cr-Commit-Position: refs/heads/master@{#424533}
(cherry picked from commit 83e4f9ac895d5b42a4b114f3ef964676a40476ff)

Committed:
https://chromium.googlesource.com/chromium/src/+/68f883645ff0c2f46fa75128af06...
==========

[kenrb, 2016-11-03 20:59:07]

Committed patchset #1 (id:1) manually as
68f883645ff0c2f46fa75128af0642e87e7095bd.