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

libcef/browser/chrome_browser_process_stub.cc

@@ -372,3 +372,8 @@ ChromeBrowserProcessStub::resource_coordinator_parts() {
   NOTREACHED();
   return nullptr;
 }
+
+BuildState* ChromeBrowserProcessStub::GetBuildState() {
+  NOTREACHED();
+  return nullptr;
+}