Use dummy implementation of create_sys_info for Chromium Web runtime.

CWR currently uses the shlib implementation which is not populating all
the required fields. As a result Widevine DRM fails to initialize
leading to media playback failures. This CL adds a workaround for that
until CastSysInfo is properly wired up.

Bug: b/200565349, b/200723084
Change-Id: I6ee7f7e1adda853ab5d76dcaf450c9d7e7581be3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3173917


Reviewed-by: Sean Topping <seantopping@chromium.org>
Reviewed-by: Ryan Keane <rwkeane@google.com>
Commit-Queue: Anirudh Tadakamala <antadaka@google.com>
Cr-Commit-Position: refs/heads/main@{#923643}