<webview> Fix crash when closing chrome://chrome-signin

<webview> Fix crash when closing chrome://chrome-signin

This fixes a browser crash with OOPIF-based webviews. When two instances
of chrome://chrome-signin are opened in browser tabs, closing either one
of them leads to a crash.

The embedding WebContentsImpl in its destructor will attempt to update
screen rects for child WebContentsImpl. The children will fail to locate
their parent due to their node Id not being kInvalid despite the node no
longer existing (destroyed earlier in the parent WebContentsImpl dtor).

~ No longer notify children about screen rect changes when being
  destroyed.
+ Add regression test.

BUG=667708
Review-Url: https://codereview.chromium.org/2519333007
Cr-Commit-Position: refs/heads/master@{#434570}
(cherry picked from commit 9f43b0110e3e4b47064b067fecc30ca2ce2c193e)

Committed: https://chromium.googlesource.com/chromium/src/+/57e104b5bbebdf3c7319ff89239dc9ebef7fd7c9

[wjmaclean, 2016-12-01 19:51:22]

Description was changed from

==========
<webview> Fix crash when closing chrome://chrome-signin

This fixes a browser crash with OOPIF-based webviews. When two instances
of chrome://chrome-signin are opened in browser tabs, closing either one
of them leads to a crash.

The embedding WebContentsImpl in its destructor will attempt to update
screen rects for child WebContentsImpl. The children will fail to locate
their parent due to their node Id not being kInvalid despite the node no
longer existing (destroyed earlier in the parent WebContentsImpl dtor).

~ No longer notify children about screen rect changes when being
  destroyed.
+ Add regression test.

BUG=667708

Review-Url: https://codereview.chromium.org/2519333007
Cr-Commit-Position: refs/heads/master@{#434570}
(cherry picked from commit 9f43b0110e3e4b47064b067fecc30ca2ce2c193e)
==========

to

==========
<webview> Fix crash when closing chrome://chrome-signin

This fixes a browser crash with OOPIF-based webviews. When two instances
of chrome://chrome-signin are opened in browser tabs, closing either one
of them leads to a crash.

The embedding WebContentsImpl in its destructor will attempt to update
screen rects for child WebContentsImpl. The children will fail to locate
their parent due to their node Id not being kInvalid despite the node no
longer existing (destroyed earlier in the parent WebContentsImpl dtor).

~ No longer notify children about screen rect changes when being
  destroyed.
+ Add regression test.

BUG=667708

Review-Url: https://codereview.chromium.org/2519333007
Cr-Commit-Position: refs/heads/master@{#434570}
(cherry picked from commit 9f43b0110e3e4b47064b067fecc30ca2ce2c193e)

Committed:
https://chromium.googlesource.com/chromium/src/+/57e104b5bbebdf3c7319ff89239d...
==========

[wjmaclean, 2016-12-01 19:51:23]

Committed patchset #1 (id:1) manually as
57e104b5bbebdf3c7319ff89239dc9ebef7fd7c9.