Google Inc’s revenue fell short of Wall Street’s expectations as growth in Internet advertising slowed in the most-recent quarter, offsetting a modest improvement in ad pricing, sending its shares down about 3 percent. Shares of Google fell 2.7 percent to $510.11 in extended trading on Thursday. Google posted $16.52 billion in revenue for the three months ended Sept. 30, compared to $13.75 billion in the year ago period.