A series of changes to Google Chrome OS's source code provide the clearest indication yet that the search giant is preparing its notebook OS for the tablet form factor.

Google has toyed with the idea of bringing Chrome OS to tablets; it even made mockups and concepts of a tablet running Chrome OS last year, and it's had intentions to include touch for a while. Still, former Google CEO Eric Schmidt stated last year that Android was for touch and Chrome OS was for keyboards.

The line between Android and Chrome OS is about to be blurred though, according to CNET. It has uncovered several changes to the Chrome and Chrome OS source code that indicate work is being done on a tablet version. The changes include new references to a touch version of Chrome OS, references to tablet Chrome OS devices and a touch-optimized new tab page.

If Google really is preparing for the release of a tablet version of Chrome OS, what does that mean for its existing tablet OS, Android Honeycomb? The most prominent tablet running Honeycomb, the Motorola Xoom, has sold around 100,000 units, an OK start for a new device running a new OS but nothing compared with iPad 2 sales.

Is Google testing Chrome OS on tablets as an experiment, or does it plan to try a different strategy to compete with the iPad? One thing's for sure: It won't be long until we find out.