Use parentheses for multi-line method calls

Own style guide says we should be using parentheses for method calls
with arguments.

railties/lib/rails/application.rb

@@ -174,8 +174,9 @@ def key_generator
       # team. Details at https://github.com/rails/rails/pull/6952#issuecomment-7661220
       @caching_key_generator ||=
         if secret_key_base
-          ActiveSupport::CachingKeyGenerator.new \
+          ActiveSupport::CachingKeyGenerator.new(
             ActiveSupport::KeyGenerator.new(secret_key_base, iterations: 1000)
+          )
         else
           ActiveSupport::LegacyKeyGenerator.new(secrets.secret_token)
         end
@@ -400,8 +401,9 @@ def secrets
         secrets.secret_token ||= config.secret_token
 
         if secrets.secret_token.present?
-          ActiveSupport::Deprecation.warn \
+          ActiveSupport::Deprecation.warn(
             "`secrets.secret_token` is deprecated in favor of `secret_key_base` and will be removed in Rails 6.0."
+          )
         end
 
         secrets
@@ -424,8 +426,9 @@ def secret_key_base
       if Rails.env.test? || Rails.env.development?
         Digest::MD5.hexdigest self.class.name
       else
-        validate_secret_key_base \
+        validate_secret_key_base(
           ENV["SECRET_KEY_BASE"] || credentials.secret_key_base || secrets.secret_key_base
+        )
       end
     end
 
@@ -464,10 +467,11 @@ def credentials
     #
     #   Rails.application.encrypted("config/special_tokens.yml.enc", key_path: "config/special_tokens.key")
     def encrypted(path, key_path: "config/master.key", env_key: "RAILS_MASTER_KEY")
-      ActiveSupport::EncryptedConfiguration.new \
+      ActiveSupport::EncryptedConfiguration.new(
         config_path: Rails.root.join(path),
         key_path: Rails.root.join(key_path),
         env_key: env_key
+      )
     end
 
     def to_app #:nodoc:

railties/lib/rails/generators/rails/credentials/credentials_generator.rb

@@ -31,10 +31,11 @@ def add_credentials_file_silently(template = nil)
 
       private
         def credentials
-          ActiveSupport::EncryptedConfiguration.new \
+          ActiveSupport::EncryptedConfiguration.new(
             config_path: "config/credentials.yml.enc",
             key_path: "config/master.key",
             env_key: "RAILS_MASTER_KEY"
+          )
         end
 
         def credentials_template