chore: cherry-pick 8f054c5df2 and de1dbdb608 from chromium

[ppontes]

M86-LTS: Add null pointer check in RenderWidgetHostInputEventRouter

We have some crashes in RenderWidgetHostInputEventRouter class, we are
adding some null pointer check in this class to avoid the crash.

(cherry picked from commit 5f47666b79ac7ded20e1c7657037498561bd3352)

Bug: 1155297
Change-Id: I3b63d5748523ae2ce8ab469832adfc75d586e411
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2818680
Reviewed-by: Charlie Reis creis@chromium.org
Commit-Queue: Lan Wei lanwei@chromium.org
Cr-Original-Commit-Position: refs/heads/master@{#871108}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2838329
Reviewed-by: Lan Wei lanwei@chromium.org
Commit-Queue: Achuith Bhandarkar achuith@chromium.org
Owners-Override: Achuith Bhandarkar achuith@chromium.org
Cr-Commit-Position: refs/branch-heads/4240@{#1617}
Cr-Branched-From: f297677702651916bbf65e59c0d4bbd4ce57d1ee-refs/heads/master@{#800218}

==========

M86-LTS: Add weak pointer to RWHIER::FrameSinkIdOwnerMap and RWHIER::TargetMap

In RWHIER::FrameSinkIdOwnerMap and RWHIER::TargetMap, we change raw
pointer of RenderWidgetHostViewBase to weak pointer, such as
using FrameSinkIdOwnerMap = std::unordered_map<viz::FrameSinkId,
base::WeakPtr,
viz::FrameSinkIdHash>;
using TargetMap = std::map<uint32_t,
base::WeakPtr>;

This CL should fix the crash of stale pointer.

(cherry picked from commit 3e3e3cf7036d7e33a4d68b8416ae25730f9eee1d)

Bug: 1155297
Change-Id: I5b3270882ef06ae48c86bd460261723c7113953d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2792344
Reviewed-by: James MacLean wjmaclean@chromium.org
Reviewed-by: Aaron Colwell acolwell@chromium.org
Commit-Queue: Lan Wei lanwei@chromium.org
Cr-Original-Commit-Position: refs/heads/master@{#870013}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2838587
Owners-Override: Achuith Bhandarkar achuith@chromium.org
Auto-Submit: Achuith Bhandarkar achuith@chromium.org
Reviewed-by: Lan Wei lanwei@chromium.org
Cr-Commit-Position: refs/branch-heads/4240@{#1616}
Cr-Branched-From: f297677702651916bbf65e59c0d4bbd4ce57d1ee-refs/heads/master@{#800218}

Notes: Security: backported fix to chromium:1155297.

[release-clerk]

Release Notes Persisted

Security: backported fix to chromium:1155297.