Bug 792603 - Disable Fennec's reader mode entirely on low-memory platforms. r=lucasr

mobile/android/chrome/content/browser.js

@@ -3207,6 +3207,11 @@ Tab.prototype = {
           }
         });
 
+        // For low-memory devices, don't allow reader mode since it takes up a lot of memory.
+        // See https://bugzilla.mozilla.org/show_bug.cgi?id=792603 for details.
+        if (Cc["@mozilla.org/xpcom/memory-service;1"].getService(Ci.nsIMemory).isLowMemoryPlatform())
+          return;
+
         // Once document is fully loaded, parse it
         Reader.parseDocumentFromTab(this.id, function (article) {
           // Do nothing if there's no article or the page in this tab has