Add ModifyWindowInfo and GetAppId interfaces for LacrosSaveHandler.

Add the ModifyWindowInfo interface for LacrosSaveHandler to save the
window info for the Lacros window.

Add the GetAppId interface for LacrosSaveHandler to get the app id for
the Lacros window.

Add unit tests to verify LacrosSaveHandler.

BUG=1239984

Change-Id: I2d3fd6b7c9ffc7479cb575a0277b09c674391eef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3365930


Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Commit-Queue: Nancy Wang <nancylingwang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#956795}