Add Support for Setting Master Volume

[ajussak]

Currently, there is no proper way to control the master volume of a Chromium instance when using JCEF. This can be problematic when trying to manage audio output, as there is no built-in API for adjusting the volume. I tried to work around this issue using JavaScript (<audio> and <video> element controls), but this approach is not stable or convenient, especially for global volume control across multiple media sources.

Solution suggested I would like to have an API or method in JCEF that allows setting the master volume for the Chromium instance. This functionality should provide seamless control over all audio sources within the Chromium instance, making it easier to manage audio playback without unreliable workarounds.

Alternatives considered

• Using JavaScript to control volume levels, but this only works for specific elements (e.g., <audio> and <video> tags) and is not reliable as a global solution.
• Managing system-level audio controls, but this affects the entire system rather than just the Chromium instance.