First, this started in 2012. Second, it wasn't Google - it was when Krizhevsky et al published their seminal work. Realistically, Google was slow to adopt to GPUs at the time, which I understand even contributed to Prof Ng's departure. It was Baidu who launched the first large scale deep-learning based image search, well ahead of Google.
Google has certainly caught up, but nobody can say they started it (and be taken seriously).
http://www.cs.toronto.edu/~fritz/absps/tics.pdf
Here is a google tech talk from 2007:
https://www.youtube.com/watch?v=AyzOUbkUf3M
Companies didn't pick it up until more recently. GPU-ification happened in 2009 with Ng's group:
http://robotics.stanford.edu/~ang/papers/icml09-LargeScaleUn...
And yes, Krizhevsky et al (Hinton's lab) applied GPU deep learning to ImageNet in 2010:
https://papers.nips.cc/paper/4824-imagenet-classification-wi...
The ImageNet paper is from 2012, not 2010. That's when the computer vision community really went "wow". IIRC, almost every entry in ImageNet 2013 was using CNNs.
Is using a GPU "essential" for something to be deep learning? I'd always thought that the important part was some sort of hierarchical representation learning.
GPUs certainly help, in that you don't want to wait all day while your code does that, but they're not necessary.
> the basic calculations in the network happen ultimately in the form of a simple multiplication where the output Y is just the input X weighted (feedforward multiplied by W, the Weight). Y = W * X
All NNs are linear models? Wut?