Transparent background in web application

Verified on master targetting Needlefish. If I make html5 launcher transparent using appinfo.json, and remove the background image provided by launcher application, background is black instead of showing html5 background.

Indeed, nice catch!

https://github.com/webosose/chromium68/blob/%4039.agl.guppy/src/neva/app_runtime/webview.cc#L498

Through this function, Chromium renderer background can be set to transparent via SetBackgroundColor. The latter seems to be implemented by the Aura Shell window manager.

According to @José Dapena Paz, it's definitely possible to have transparent webapps. There is an appinfo entry in webOS for "isTransparent" that calls SetTransparentBackground in WebOS webview. That sets the webview background color to transparent instead of black.

We have to expose the same behavior to AGL WAM.

We know there is a concept of window opacity in Chromium from:
https://chromium-review.googlesource.com/c/chromium/src/+/1520666

Per https://lf-automotivelinux.atlassian.net/browse/SPEC-2266#icft=SPEC-2266, this patch was backported into AGL Chromium. This is a hint that maybe it's possible to do transparent web applications.