So wait... they overtook it in SALES or SHARE? Kinda a big difference...
By definition they are exactly the same.
"Unit market share: The units sold by a particular company as a percentage of total market SALES, measured in the same units."
Unit market share (%) = 100 * Unit SALES / Total Market Unit SALES
I think that what you mean by SHARE is Unit market share, while what you mean by SALES is actually Revenue market share. Revenue market share differs from unit market share in that it reflects the prices at which goods are sold.
Both Unit market share and Revenue market share are correct and accepted definitions of market share, though they actually show different data. From what I could gather checking the original source, and other sources that show global unit market share I'm more inclined to think the article means Unit market share.
On a side note, it's important to notice how Windows Phones are declining globally, specially in the biggest market of the world, China, where they have gone from a not very significant 3.5% in October 2013 to a negligible <1% in late 2014.