It's becoming pretty clear that Google (NASDAQ:GOOGL) only loves Motorola Mobility for its smartphone brains. The set-top box division might have been a good fit with the Google Fiber project and other tie-ins to the living room, but that idea was just put on ice -- permanently.

Cable industry infrastructure veteran Arris (NASDAQ:ARRS) has agreed to take that set-top box business off Google's hands for a cool $2.35 billion. The cash-plus-stock deal will give Google a 16% ownership stake in Arris. Big G vaults right past investment firm BlackRock's (NYSE:BLK) 10% holdings to become Arris' largest shareholder.

Arris will own some of Motorola's technology patents and take a license to "a wide array" of the patents remaining under the Google umbrella.

Google shares were largely unchanged by the announcement, but Arris jumped as much as 10% on the news.

The deal will instantly triple Arris' revenue and is expected to add to the buyer's earnings right away, and should close in the first half of 2013. Arris will fund the $2 billion cash portion of the contract with new debt. The deal creates an end-to-end cable equipment beast to rival Cisco Systems (NASDAQ:CSCO), which also builds both back-end systems and customer-facing equipment for the cable TV market.

So what's in it for Google? You might think that Google signed on the dotted line to remove the risk of pending TiVo (NASDAQ:TIVO) litigation, but that's not exactly right: Google actually agreed to indemnify Arris and pick up the legal bill in case TiVo wins big.

After this transaction, the effective price tag for Motorola Mobility shrinks to roughly $10 billion. Hardware sales aren't exactly in Google's wheelhouse, so the move should also reduce the operational risk of that massive acquisition.

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