Warn about removed protocol APIs

atom/browser/api/lib/protocol.coffee

@@ -3,4 +3,22 @@ throw new Error('Can not initialize protocol module before app is ready') unless
 
 protocol = process.atomBinding('protocol').protocol
 
+# Warn about removed APIs.
+logAndThrow = (callback, message) ->
+  console.error message
+  if callback then callback(new Error(message)) else throw new Error(message)
+protocol.registerProtocol = (scheme, handler, callback) ->
+  logAndThrow callback,
+              'registerProtocol API has been replaced by the
+               register[File/Http/Buffer/String]Protocol API family, please
+               switch to the new APIs.'
+protocol.isHandledProtocol = (scheme, callback) ->
+  logAndThrow callback,
+              'isHandledProtocol API has been replaced by isProtocolHandled.'
+protocol.interceptProtocol = (scheme, handler, callback) ->
+  logAndThrow callback,
+              'interceptProtocol API has been replaced by the
+               intercept[File/Http/Buffer/String]Protocol API family, please
+               switch to the new APIs.'
+
 module.exports = protocol