Update to Chromium version 88.0.4324.0 (#827102)

- Mac: Xcode 12.2 and the MacOS 11.0 SDK are now required for building.
- MacOS 10.10 (Yosemite) is no longer supported (see https://crbug.com/1126056).
- Flash is no longer supported (see https://www.chromium.org/flash-roadmap).

libcef/browser/net/scheme_handler.h

@@ -18,9 +18,6 @@ namespace scheme {
 // Register the internal scheme handlers that can be overridden.
 void RegisterInternalHandlers(CefIOThreadState* iothread_state);
 
-// Used to fire any asynchronous content updates.
-void DidFinishLoad(CefRefPtr<CefFrame> frame, const GURL& validated_url);
-
 }  // namespace scheme
 
 #endif  // CEF_LIBCEF_BROWSER_NET_SCHEME_HANDLER_H_