[TLDR: Bravo Google, but I think we're attacking the issue on the wrong side]
offering a free pass into code school for underrepresented groups is touching the problem too late.
If Google were genuinely interested in generating a more diverse, technically sharp population, they'd be looking at elementary, middle, and high schools (notice the AND). Education is an iterative process, adults that love to code and code well are either savants, or have had a decent education growing up. This doesn't mean we need One Laptop Per Kindergartener, but it would help if there were learning materials and dedicated staff in elementary schools. It would help if there were rudimentary computer labs in middle schools that did more than surf a subset of the internet. It would help if math was as celebrated as sports in high schools.
Many of the people who will be taking these coding classes will not have had the background in math that strengthens critical, algorithmic thinking - it doesn't mean they can't develop that thinking, but so long as their background is limited to the 'last step' (learning to code), they will continue to be hired on as quota-fillers.
I do applaud Google for doing something. Giving these underrepresented groups easier access to some kind of technical education should have a positive effect on the observed hiring-disparities. However, addressing the issue at this 'last step' level will not be nearly as powerful as improving the limping-machine that is our public education system.
I do think we are overly concerned with the racial make-up of [company x]. Most companies are going to hire the candidate that will help them make the most money. The lack of diversity in [company x] is likely reflecting the lack of a skillset in population subsets y and z. The lack of diversity is a symptom, not the problem. It's just easier to point an angry finger at [big faceless corporation] than at our own communities.