Issue 5347 - Check for contextMenus API support

ext/background.js

Index: ext/background.js
===================================================================
--- a/ext/background.js
+++ b/ext/background.js
@@ -70,17 +70,21 @@
   /* Pages */
 
   let Page = ext.Page = function(tab)
   {
     this.id = tab.id;
     this._url = tab.url && new URL(tab.url);
 
     this.browserAction = new BrowserAction(tab.id);
-    this.contextMenus = new ContextMenus(this);
+
+    // Firefox for Android does not support context menus.
+    // https://bugzilla.mozilla.org/show_bug.cgi?id=1269062
+    if ("contextMenus" in chrome)

[Wladimir Palant, 2017/08/16 13:21:56]

I don't think that this change is necessary. It should be ok to create this
instance regardless, even if it isn't used.

[Manish Jethani, 2017/08/16 19:39:09]

Done.

+      this.contextMenus = new ContextMenus(this);
   };
   Page.prototype = {
     get url()
     {
       // usually our Page objects are created from Chrome's Tab objects, which
       // provide the url. So we can return the url given in the constructor.
       if (this._url)
         return this._url;
@@ -418,17 +422,19 @@
 
   /* Context menus */
 
   let contextMenuItems = new ext.PageMap();
   let contextMenuUpdating = false;
 
   let updateContextMenu = () =>
   {
-    if (contextMenuUpdating)
+    // Firefox for Android does not support context menus.
+    // https://bugzilla.mozilla.org/show_bug.cgi?id=1269062
+    if (!("contextMenus" in chrome) || contextMenuUpdating)
       return;
 
     contextMenuUpdating = true;
 
     chrome.tabs.query({active: true, lastFocusedWindow: true}, tabs =>
     {
       chrome.contextMenus.removeAll(() =>
       {