midicast should be a browser_action rather than a page_action, to ensure the controls can be opened even when there are no MIDIs on the current page. Still, it would be a nice user experience for the icon to change when there are MIDIs available.
chrome.declarativeContent.SetIcon ought to be able to handle this, but it doesn't work with browser actions right now. Poke Devlin about this, and see when it's fixed. Then, use it.
midicast should be a
browser_actionrather than apage_action, to ensure the controls can be opened even when there are no MIDIs on the current page. Still, it would be a nice user experience for the icon to change when there are MIDIs available.chrome.declarativeContent.SetIconought to be able to handle this, but it doesn't work with browser actions right now. Poke Devlin about this, and see when it's fixed. Then, use it.