How to ground a 2 prong plug electronic?
The easiest way to protect against leakage to the aluminum channel is to install a Ground Fault Circuit Interrupter (GFCI) - also known as a Residual Current Detector (RCD) in the AC power supply to the LED strip. 

This will protect anyone who might be subject to electric shock.

[Edit] A GFCI works by monitoring the current difference between the Line and Neutral lines. If a leakage path develops from the Line lead to Ground, the GFCI detects that difference and trips.