Guest View is a mechanism for embedding a page inside another page. Unlike iframes, the embedded content has a distinct FrameTree. See the FrameTree explainer for details.
Guest View is the core implementation of several embedding features implemented in the //extensions and //chrome layers. Notable examples include:
Guest Views are currently implemented using inner WebContents. By end of 2024, we plan to migrate Guest Views to use MPArch like other features which nest FrameTrees.
For debugging <webview>, the Browser Sample [source] app serves as a basic demo. To test Chrome Apps on platforms other than ChromeOS:
chrome
with --disable-features=ChromeAppsDeprecation
.chrome://extensions/
, enable developer mode and load the app's source as an unpacked extension.chrome://apps/
.