The graph shows how many cores are being used by Android and the web browser. It doesn’t show how much the core is being used (that comes in a moment) but it shows if the core is being utilized at all. If Chrome was single-threaded then you would expect to see one or two cores in use and maybe a blip up to 3 or 4 cores occasionally. However we don’t see that. What we see is the opposite, four cores are being used and it occasionally dips down to two. In the browsing test I didn’t spend time reading the pages that loaded, as that would have resulted in no CPU use. However I waited until the page was loaded and rendered, and then I moved on to the next page.
Here is a graph showing how much each core was utilized. This is an averaged-out graph (as the real one is a scary scrawl of lines). This means that the peak usages are shown as less. For example the peak on this graph is just over 90%, however the raw data shows that some of the cores hit 100% multiple times during the test run. However it still gives us a good representation of what was happening.