Limited the support for the full screen mode to Chrome and Firefox.

bigbluebutton-html5/app/client/globals.coffee

@@ -150,6 +150,9 @@ Handlebars.registerHelper 'isPortraitMobile', () ->
 Handlebars.registerHelper 'isMobile', () ->
   isMobile()
 
+Handlebars.registerHelper 'isMobileChromeOrFirefox', () ->
+  isMobile() and ((getBrowserName() is 'Chrome') or (getBrowserName() is 'Firefox'))
+
 Handlebars.registerHelper "meetingIsRecording", ->
   Meteor.Meetings.findOne()?.recorded # Should only ever have one meeting, so we dont need any filter and can trust result #1
 
@@ -489,7 +492,11 @@ Handlebars.registerHelper "visibility", (section) ->
 
 # determines which browser is being used
 @getBrowserName = () ->
-  if navigator.userAgent.match(/Safari/i)
+  if navigator.userAgent.match(/Chrome/i)
+    return 'Chrome'
+  else if navigator.userAgent.match(/Firefox/i)
+    return 'Firefox'
+  else if navigator.userAgent.match(/Safari/i)
     return 'Safari'
   else if navigator.userAgent.match(/Trident/i)
     return 'IE'

bigbluebutton-html5/app/client/views/whiteboard/whiteboard.html

@@ -1,7 +1,7 @@
 <template name="whiteboard">
     <div id="{{id}}" {{visibility name}} class="component gradientBar">
         <h3 id="whiteboard-navbar" class="title">
-            {{#if isMobile}}
+            {{#if isMobileChromeOrFirefox}}
                 {{> makeButton btn_class="fullscreenWhiteboardButton" i_class="glyphicon glyphicon-fullscreen"}}
             {{/if}}
             <span class="glyphicon glyphicon-pencil"></span>