Add explanation for screen sharing on Firefox

Fix #94

lib/Vroom/I18N/en.pm

@@ -220,6 +220,16 @@ our %Lexicon = (
   "SCREEN_SHARING_CANCELLED"             => "Screen sharing has been cancelled",
   "EXTENSION_REQUIRED"                   => "An extension is required",
   "VROOM_CHROME_EXTENSION"               => "To enable screen sharing, you need to install an extension. Click on the following link and refresh this page",
+  "ALLOW_SCREEN_SHARING"                 => "You have to allow screen sharing",
+  "ALLOW_SCREEN_SHARING_ON_FF_s"         => "For security reasons, your browser do not allow screen sharing by default. " .
+                                            "To enable it, please follow these steps:<br>" .
+                                              "<ol>" .
+                                              "  <li>Open a new tab, and type <b>about:config</b> in the address bar</li>" .
+                                              "  <li>Accept the warning by clicking on the \"<i>I'll be careful, I promise !</i>\" button</li>" .
+                                              "  <li>Search for <b>screensharing</b> in the search bar</li>" .
+                                              "  <li>Double click on <b>media.getusermedia.screensharing.allowed_domains</b> to edit it</li>" .
+                                              "  <li>Add <b>%s</b> at the end of the list</li>" .
+                                              "</ol>",
   "PAUSE_MOH"                            => "Play/Pause music",
   "WAIT_WITH_MUSIC"                      => "Why don't you listen to some music while waiting for others ?",
   "ALONE_IN_ROOM"                        => "Please wait a moment while nobody is here yet",

lib/Vroom/I18N/fr.pm

@@ -228,6 +228,17 @@ our %Lexicon = (
     "EXTENSION_REQUIRED"                        => "Une extension est nécessaire",
     "VROOM_CHROME_EXTENSION"                    => "Pour activer le partage d'écran, vous devez installer une extension, cliquez sur le " .
                                                    "lien ci-dessous, puis raffraîchissez cette page",
+    "ALLOW_SCREEN_SHARING"                      => "Vous devez autoriser le partage d'écran",
+    "ALLOW_SCREEN_SHARING_ON_FF_s"              => "Par mesure de sécurité, votre navigateur n'autorise pas le partgage d'écran par défaut. " .
+                                                   "Pour l'activer, suivez ces étapes:<br>" .
+                                                   "<ol>" .
+                                                   "  <li>Ouvrez un nouvel onglet, et tapez <b>about:config</b> dans la barre d'adresse</li>" .
+                                                   "  <li>Validez l'avertissement en cliquant sur le bouton \"<i>Je ferai attention, promis !</i>\"</li>" .
+                                                   "  <li>Recherchez <b>screensharing</b> à l'aide de la barre de recherche</li>" .
+                                                   "  <li>Double cliquez sur <b>media.getusermedia.screensharing.allowed_domains</b> pour le modifier</li>" .
+                                                   "  <li>Ajoutez <b>%s</b> à la fin de la liste</li>" .
+                                                   "  <li>Vous pouvez désormais partager votre écran</li>" .
+                                                   "</ol>",
     "PAUSE_MOH"                                 => "Mettre en pause ou jouer la musique d'attente",
     "WAIT_WITH_MUSIC"                           => "Un peu de musique en attendant d'autres participants ?",
     "ALONE_IN_ROOM"                             => "Patientez quelques instants le temps que d'autres personnes vous rejoignent",

public/js/vroom.js

@@ -1773,6 +1773,9 @@ function initVroom(room) {
           // This error usually means you have denied access (old flag way)
           // or you cancelled screen sharing (new extension way)
           // or you select no window (in Firefox)
+          else if (err.name === 'PermissionDeniedError' && $.browser.mozilla){
+            $('#firefoxShareScreenModal').modal('show');
+          }
           else if (err.name === 'PERMISSION_DENIED' ||
                    err.name === 'PermissionDeniedError' ||
                    err.name === 'ConstraintNotSatisfiedError'){

templates/default/join.html.ep

@@ -275,6 +275,25 @@
         </div>
       </div>
     </div>
+    <div class="modal fade" role="dialog" id="firefoxShareScreenModal" aria-labelledby="firefoxShareScreenModal" aria-hidden="true">
+      <div class="modal-dialog modal-lg">
+        <div class="modal-content">
+          <div class="modal-header">
+            <button type="button" class="close" data-dismiss="modal" aria-hidden="true">
+              &times;
+            </button>
+            <h4 class="modal-title">
+              <%=l 'ALLOW_SCREEN_SHARING' %>
+            </h4>
+          </div>
+          <div class="modal-body">
+            <p>
+              <%== sprintf $self->l('ALLOW_SCREEN_SHARING_ON_FF_s'), $self->req->url->to_abs->host %>
+            </p>
+          </div>
+        </div>
+      </div>
+    </div>
     <div class="modal fade" role="dialog" id="noWebrtcSupport" aria-labelledby="noWebrtcSupport" aria-hidden="true">
       <div class="modal-dialog modal-lg">
         <div class="modal-content">