i.e : They are internally working on self driving cars and, in particular, are looking for ways to integrate algorithm 'X' in their solution. So, google decides to setup a special filter for searches related to certain profiles that search for 'X and self driving ....Results get fed to the group conducting the work. In effect, allowing them to internally see what 'profiles of interest' are up to as it relates to Google's flagged area of interest.
It would appear that this could easily be made 'legal' under the premise that the individuals are anonymized. However, it does give google a unique advantage in being able to see 'what everyone is up to'.
The fact that they are already using people's specialized searches for flagging them for interviewing makes me strongly believe they are already internally snagging people's searches/clicked links to give them advantage on projects.
I think everyone should take a pause and consider the implications of this as they are quite damning.