Update: You can read Google's full testimony to the committee on its Public Policy Blog. Its main argument is that location-based services provide "tremendous value to consumers," but that they can't work without the trust of users, which is why it has made location sharing on Android devices "strictly opt-in."
You can also read Apple's testimony here (PDF). In it, the company's Vice President of Software Technology, Bud Tribble, flatly reasserts that "Apple does not track users' locations -- Apple has never done so and has no plans to ever do so." He also insists that the location data Apple has collected is actually the location of cellphone towers and WiFi hotspots, not the users' location, and that it is being used for a crowd-sourced database as it has previously stated. As an independent expert also testifying pointed out, however, that data could still be used to pin down a location or trace a person's movements to as close as a few hundred feet or so -- assuming they aren't in a rural area with few WiFi hotspots and cellphone towers.