See jchen's mobile-firefox-dev post [3], copied below for convenience: With the latest v4 support library, we can also start using SimpleArrayMap/ArrayMap for some of the places where we've been using HashMap. SimpleArrayMap [1] and ArrayMap [2] have better memory characteristics than HashMap for a small perf tradeoff. [1] http://developer.android.com/reference/android/support/v4/util/SimpleArrayMap.html [2] http://developer.android.com/reference/android/support/v4/util/ArrayMap.html --- Awaiting bug 990161, the support library update, to land, of course. [3]: https://mail.mozilla.org/pipermail/mobile-firefox-dev/2014-March/000584.html

;)

via bug 990161 comment 12: > Because we are lifting the source for SwipeRefreshLayout, > we do not need to upgrade the support library anymore. Guess this is infeasible - closing.

We'll want to work on this when the support library gets upgraded eventually.

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