Update to Chromium version 82.0.4085.0 (#749737)

- Building on macOS now requires the 10.15 SDK. Xcode 11.3 is recommended as
  Xcode 11.4 is not currently supported (see https://crbug.com/1065146).
- Jumbo build configuration is no longer supported.

Chromium is skipping the M82 release and consequently no CEF 4085 branch will
be created. For details on the Chromium decision see
https://groups.google.com/a/chromium.org/d/msg/chromium-dev/Vn7uzglqLz0/JItlSrZxBAAJ

tools/automate/automate-git.py

@@ -1150,10 +1150,9 @@ if os.path.exists(cef_dir) and not is_git_checkout(cef_dir):
   raise Exception("Not a valid CEF Git checkout: %s" % (cef_dir))
 
 # Determine the CEF download URL to use.
-if options.url == '':
+cef_url = options.url.strip()
+if cef_url == '':
   cef_url = cef_git_url
-else:
-  cef_url = options.url
 
 # Verify that the requested CEF URL matches the existing checkout.
 if not options.nocefupdate and os.path.exists(cef_dir):