It seems Google is working on a speed test service that will be built within Google Search and can be used simply by searching for "check internet speed" or something similar.
The feature is being developed partnership with Measurement Lab (or M-Lab), who will be doing the actual testing. The test will check your download and upload speed and latency.
The service is not yet active so we don't really know what it looks like. For what it's worth, Bing has had a speed test built into its search results for a while now (accessed by searching for "speed test") and even Netflix recently released, although simplistic, speed test service at fast.com. And then of course there is the most popular option from Ookla.
There is no known timeline for when this feature will be released to the public.
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