Firefox for Android now comes with a built-in ad blocker
http://festwiz.blogspot.com/2015/11/firefox-for-android-now-comes-with.html
Mozilla Firefox 42 for Android has seem to have done away the need to have extensions like Adblock plus installed as the functionality is there without the need for any add-ons. The Adblock functionality is activated thdough the Private Browsing feature or Incognito Mode. This now comes with tracking protection, which "blocks certain Web elements that could be used to record your behavior across sites", according to Mozilla's changelog. In effect, this function blocks ads too, since those fit the bill quite well. It also blocks tracking cookies and social sharing buttons, for example.
Firefox 42 for Android has other new stuff in it as well, such as the ability to open external URLs from Android apps in the background, family-friendly browsing when you create a restricted profile on a tablet, scrollable tabs for panels navigation, direct voice input support for searching from the URL bar, and a new mobile login manager.
Source
Firefox 42 for Android has other new stuff in it as well, such as the ability to open external URLs from Android apps in the background, family-friendly browsing when you create a restricted profile on a tablet, scrollable tabs for panels navigation, direct voice input support for searching from the URL bar, and a new mobile login manager.
Source