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"Your main responsibility is to drive new business revenue growth with our Fortune 1000 advertisers in a specified vertical [my note: travel vertical] in one or more regions" the job listing mentions.
For now, when you enter two cities in your query, Google links to third-parties travel planning and flight-booking sites (Expedia, Hotwire, Orbitz), but the experience isn't very good: these flight-booking sites have slow search engines and intrusive ads.