Bug 947984 - Australis' view widgets shouldn't require onViewShowing/onViewHiding event handlers, r=mconley

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extra : rebase_source : 303fc1b429f08cb66c56a4fa1d541f1f7343e17c
Bug 947988 - take Australis switch-to-metro code out of CustomizableUI.jsm, r=mconley

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extra : rebase_source : 0f6e0eb71c31a1aaff2851cba08ee156a4c3164c