This article, which may be the original source, makes it clear that we're talking LPDDR3 (aka "mobile DRAM") only.
Although it makes sense if this about LPDDR3, as I think every current iDevice except the 5C and iPod use that, whereas only higher end Androids and Windows Phones use it. MacBooks are also considerably more popular relatively in the higher end regions of the market. That skews the figure considerably towards Apple. Especially considering other platforms will start moving to LPDDR4 soon.