gecko/browser/modules/ContentObservers.jsm

44 lines
1.5 KiB
JavaScript

/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* This module is for small observers that we want to register once per content
* process, usually in order to forward content-based observer service notifications
* to the chrome process through message passing. Using a JSM avoids having them
* in content.js and thereby registering N observers for N open tabs, which is bad
* for perf.
*/
"use strict";
this.EXPORTED_SYMBOLS = [];
const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
Cu.import("resource://gre/modules/Services.jsm");
let gEMEUIObserver = function(subject, topic, data) {
let win = subject.top;
let mm = getMessageManagerForWindow(win);
if (mm) {
mm.sendAsyncMessage("EMEVideo:ContentMediaKeysRequest", data);
}
};
function getMessageManagerForWindow(aContentWindow) {
let ir = aContentWindow.QueryInterface(Ci.nsIInterfaceRequestor)
.getInterface(Ci.nsIDocShell)
.sameTypeRootTreeItem
.QueryInterface(Ci.nsIInterfaceRequestor);
try {
// If e10s is disabled, this throws NS_NOINTERFACE for closed tabs.
return ir.getInterface(Ci.nsIContentFrameMessageManager);
} catch(e if e.result == Cr.NS_NOINTERFACE) {
return null;
}
}
Services.obs.addObserver(gEMEUIObserver, "mediakeys-request", false);