dlp: Fix resuming of a tab share.

When DLP tries to resume a tab share, it may fail
if the capture tracks the currently shared WebContents
using an outdated main frame id - e.g. after it was navigated
to a different page.
In this case before resuming we need to update the source using
SourceCallback, similar to "share this tab instead" feature.

Bug: 1293866
Change-Id: I4ef5e76416ec20375805af992cebcaba1044ab82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3461659
Reviewed-by: Aya Elsayed <ayaelattar@chromium.org>
Reviewed-by: Roland Bock <rbock@google.com>
Reviewed-by: Elad Alon <eladalon@chromium.org>
Commit-Queue: Sergey Poromov <poromov@chromium.org>
Cr-Commit-Position: refs/heads/main@{#971894}