follow the pattern more closely

Library/Homebrew/extend/os/dependency_collector.rb

@@ -1,3 +1,5 @@
+require "dependency_collector"
+
 if OS.mac?
   require "extend/os/mac/dependency_collector"
 elsif OS.linux?

Library/Homebrew/extend/os/linux/dependency_collector.rb

@@ -1,3 +1,5 @@
-def ant_dep(spec, tags)
+class DependencyCollector
+  def ant_dep(spec, tags)
     Dependency.new(spec.to_s, tags)
+  end
 end

Library/Homebrew/extend/os/mac/dependency_collector.rb

@@ -1,5 +1,7 @@
-def ant_dep(spec, tags)
+class DependencyCollector
+  def ant_dep(spec, tags)
     if MacOS.version >= :mavericks
       Dependency.new(spec.to_s, tags)
     end
+  end
 end