How can I set Google Chrome Canary as the default browser on Windows 8?
Control Panel > Default Programs > Set your default programs. Click on Google Chrome Canary and select "Set this program as default".
Not answering the original question, but for people like me who might stumble upon this page when searching, the way to do it on OS X Yosemite (10.10) and up is in System Preferences -> General. Before it was in Safari's setting but now it's no longer the case.
Replace YourUsernameHere with your user name. After that copy and paste the below into a text file and save it as canary.reg. then double click the file.
This will only work if you have administrative privileges on your computer. If you are doing this on a computer without admin, you can use the same setup, replacing HKEY_LOCAL_MACHINE\SOFTWARE with HKEY_CURRENT_USER\Software and replacing ChromeSxSHTML with ChromeSxSHTML with the key you can find in Regedit in HKEY_CURRENT_USER\Software\Classes\ - You'll see one named ChromeSSHTML.<some random string here>. Copy this and replace ChromeSxSHTML with it.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ChromeSxSHTML]
"URL Protocol"=""
@="Google Chrome Canary HTML Document"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ChromeSxSHTML\DefaultIcon]
@="C:\\Users\\YourUsernameHere\\AppData\\Local\\Google\\Chrome SxS\\Application\\chrome.exe,4"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ChromeSxSHTML\shell]
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ChromeSxSHTML\shell\open]
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ChromeSxSHTML\shell\open\command]
@="\"C:\\Users\\YourUsernameHere\\AppData\\Local\\Google\\Chrome SxS\\Application\\chrome.exe\" -- \"%1\""
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ChromeSxSURL]
@="Google Chrome Canary URL"
"FriendlyTypeName"="Google Chrome Canary URL"
"URL Protocol"=""
"EditFlags"=dword:00000002
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ChromeSxSURL\DefaultIcon]
@="C:\\Users\\YourUsernameHere\\AppData\\Local\\Google\\Chrome SxS\\Application\\chrome.exe,4"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ChromeSxSURL\shell]
@="open"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ChromeSxSURL\shell\open]
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ChromeSxSURL\shell\open\command]
@="\"C:\\Users\\YourUsernameHere\\AppData\\Local\\Google\\Chrome SxS\\Application\\chrome.exe\" -- \"%1\""
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\FirefoxURL\shell\open\ddeexec]
@="\"%1\",,0,0,,,,"
"NoActivateHandler"=""
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\FirefoxURL\shell\open\ddeexec\Application]
@="Google Chrome Canary"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\FirefoxURL\shell\open\ddeexec\Topic]
@="WWW_OpenURL"
[HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\http\UserChoice]
"Progid"="ChromeSxSHTML"
[HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\https\UserChoice]
"Progid"="ChromeSxSHTML"
[HKEY_CLASSES_ROOT\.htm]
@="ChromeSxSHTML"
"Content Type"="text/html"
"PerceivedType"="text"
[HKEY_CLASSES_ROOT\.html]
@="ChromeSxSHTML"
"Content Type"="text/html"
"PerceivedType"="text"