All browserAction / pageAction methods support callbacks in Chrome 67+

[Rob--W]

Chrome 67+ supports callbacks for all pageAction / browserAction methods, since https://bugs.chromium.org/p/chromium/issues/detail?id=451320#c10

The polyfill should pass a callback for these methods, in order to catch any errors. The logic to do so is described at #13 (comment)

[rpl]

We currently call these API method with the callback first (at least the ones that were already identified when we were working on #59), and then if the call with the callback is raising an error, we retry the API call without the callback:

webextension-polyfill/src/browser-polyfill.js

Lines 135 to 156 in a7cbdcc

	if (metadata.fallbackToNoCallback) {
	// This API method has currently no callback on Chrome, but it return a promise on Firefox,
	// and so the polyfill will try to call it with a callback first, and it will fallback
	// to not passing the callback if the first call fails.
	try {
	target[name](...args, makeCallback({resolve, reject}, metadata));
	} catch (cbError) {
	console.warn(`${name} API method doesn't seem to support the callback parameter, ` +
	"falling back to call it without a callback: ", cbError);
	target[name](...args);
	// Update the API method metadata, so that the next API calls will not try to
	// use the unsupported callback anymore.
	metadata.fallbackToNoCallback = false;
	metadata.noCallback = true;
	resolve();
	}
	} else if (metadata.noCallback) {
	target[name](...args);
	resolve();

@Rob--W Do you mind to check if this is working as expected in Chrome 67+?
and if there are any other API methods that should be marked with the same metadata property (fallbackToNoCallback).

So that we can detail more clearly what is actually missing so that we can consider this issue as fixed.

[Rob--W]

The patch in Chrome 67 has just landed, so it will take a short while until Canary has the patch.

The following pageAction and browserAction methods are missing from api-metadata.json:

• setBadgeText
• setBadgeBackgroundColor

The following browserAction methods are missing:

• enable
• disable
• setPopup

[Rob--W]

Fixed by #125 .