PSA: site isolation is coming to <webview> tags

[Alex Moshchuk]

Hello all, 

Just a heads up that we will soon be enabling site isolation in <webview> tags.  I think some embedders cared about <webview> and its nested WebContents implementation in the past, so please let us know if you have any concerns with this.

More information is available in this doc.  Overall, this will change how <webview> tags are represented in the process model (chrome-guest:// URLs will go away), and it will make cross-process navigations and out-of-process iframes possible in <webviews>.  The changes should be all internal and transparent to web content, users, and developers, but please let us know if you encounter any issues.  We plan to start experimenting with this on stable in M105 if everything goes well.  You can try it out via chrome://flags/#enable-webview-tag-site-isolation.  The inner/outer WebContents architecture will stay as-is for now, though we're also planning to migrate away from it to MPArch in the near future.

Thanks,

Alex