I have been using Chrome Canary build for a long time now especially to try out new features and technologies that this more advanced version of Chrome offers. This nightly build of Chrome has the newest of the new Chrome features, which will be introduced in other channels of Chrome at a later stage.
Chrome Canary build can be run side-by-side with other Chrome channels (beta, dev and stable). Therefore, as Canary is a secondary installation of Chrome, you cannot set it as the default browser. However, there is a small workaround to make Chrome Canary build as your default browser in Windows and Mac.
If you are interested to make your Chrome Canary build as the default browser in Windows, here is how it is.
Download the small registry file from this forum post (required registration) and unzip it. Open the registry file and replace “YourUsernameHere” in Registry.reg with your username. Save the reg file and run it (double click).
Mac users may refer this page for making your Chrome Canary build as default browser in your Mac OS X. [Via]