dateMenu: Use icon for message indicator

Using a unicode character here means it may look quite different
from the intended style (for instance with emoji fonts). Avoid
this by providing a custom icon and use that instead.

https://bugzilla.gnome.org/show_bug.cgi?id=766368

data/gnome-shell-theme.gresource.xml

@@ -18,6 +18,7 @@
     <file>gnome-shell.css</file>
     <file>gnome-shell-high-contrast.css</file>
     <file>logged-in-indicator.svg</file>
+    <file alias="icons/message-indicator-symbolic.svg">message-indicator-symbolic.svg</file>
     <file>no-events.svg</file>
     <file>no-notifications.svg</file>
     <file>noise-texture.png</file>

data/theme/message-indicator-symbolic.svg

@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="16"
+   height="16"
+   viewBox="0 0 4.2333333 4.2333333"
+   version="1.1"
+   id="svg8">
+  <defs
+     id="defs2" />
+  <metadata
+     id="metadata5">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title></dc:title>
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <g
+     id="layer1"
+     style="display:inline"
+     transform="translate(0,-292.76667)">
+    <path
+       style="fill:#bebebe;fill-opacity:1;stroke:none;stroke-width:0.17969394"
+       d="m 3.1749998,294.88333 a 1.0583333,1.0583333 0 0 1 -1.0583332,1.05833 1.0583333,1.0583333 0 0 1 -1.0583333,-1.05833 1.0583333,1.0583333 0 0 1 1.0583333,-1.05833 1.0583333,1.0583333 0 0 1 1.0583332,1.05833 z"
+       id="path4485" />
+  </g>
+</svg>

js/ui/dateMenu.js

@@ -337,7 +337,9 @@ var MessagesIndicator = new Lang.Class({
     Name: 'MessagesIndicator',
 
     _init: function() {
-        this.actor = new St.Label({ text: '⚫', visible: false, y_expand: true,
+        this.actor = new St.Icon({ icon_name: 'message-indicator-symbolic',
+                                   icon_size: 16,
+                                   visible: false, y_expand: true,
                                    y_align: Clutter.ActorAlign.CENTER });
 
         this._sources = [];

js/ui/main.js

@@ -122,6 +122,7 @@ function start() {
     sessionMode.connect('updated', _sessionUpdated);
     Gtk.Settings.get_default().connect('notify::gtk-theme-name',
                                        _loadDefaultStylesheet);
+    Gtk.IconTheme.get_default().add_resource_path('/org/gnome/shell/theme/icons');
     _initializeUI();
 
     shellAccessDialogDBusService = new AccessDialog.AccessDialogDBus();