Tom are you the right person to own this?

A couple options:

1) All volume controls affect the Chromecast instead of the device; volume slider in the system menu, volume keys, etc.
2) If we add a Chromecast detailed view (eg. as part of tiles), you can control the volume from there.

#1 seems more reasonable when casting your screen, whereas #2 seems more reasonable when casting a tab.

@jdufault are both of these options possible?

Implementation wise this should be feasible, assuming media router has the ability to change audio. However, I don't see anything in to do this in chrome/browser/media/router, maybe it is specific to the cast extension?

cc imcheng@ to answer.

We allow changing the volume in the custom route controller in the Media Router dialog, but this is implemented with messaging in a Cast-specific format (The custom controller template rendered by the MR dialog is actually part of Cast). I don't think it's desirable for ChromeOS to try to replicate the Cast-specific messaging behavior in its native controls.

Takumi and I are currently working on the Media Controller project. Part of the effort is to define a MediaController interface that would allow you to operate on a Cast session (or other types of MediaRoute) directly via first-class APIs, e.g., SetVolume(). It sounds like this feature can leverage the work we are doing.

We have just kicked off the implementation work recently. Feel free to follow the master tracking bug if you are interested: https://bugs.chromium.org/p/chromium/issues/detail?id=684642

Thanks, imcheng! Any thoughts on when that work will be ready for us to use so we can plan accordingly?

Sorry for the late reply. My estimate is that it will be ready in early to mid Q2.

Thanks @imcheng. We'll follow the master bug.