Publish a URL property and open it on join.

activities/web/webactivity.py

@@ -32,6 +32,20 @@ class WebActivity(Activity):
 
 		self._browser.load_url(_HOMEPAGE)
 
+	def join(self, activity_ps):
+		Activity.join(self, activity_ps)
+
+		url = self._service.get_published_value('URL')
+		if url:
+			self._browser.load_url(url)
+
+	def share(self):
+		Activity.share(self)
+
+		url = self._browser.get_location()
+		if url:
+			self._service.set_published_value('URL', url)
+
 	def _title_changed_cb(self, embed, pspec):
 		self.set_title(embed.props.title)