GitLab

For GuestView types in the browser, such as <webview> in WebUI and
<extensionoptions> in WebUI, we would live status messages to appear
in the browser. This CL plumbs that information out to the embedder.

ContentsMouseEvent, LoadingStateChanged, and UpdateTargetURL are calls out to the content embedder that are used by Browser to update status indicators such as the spinner, and status text.

This CL plumbs those calls out from the guest to the embedder. This is a bit racy because guest status and embedder status can interleave but that's OK because these status texts are transient and eventually they'll settle and disappear so there's no long lasting raciness of consequence.

BUG=453216
TBR=lazyboy@chromium.org

Review URL: https://codereview.chromium.org/880983006

Cr-Commit-Position: refs/heads/master@{#314005}