Use ControlInterface for creating proxies

This removes the IPC specific (D-Bus) dependencies from FirewallManager
and ShillManager.

Bug: 24194427
TEST=Verify wifi bootstrapping on both dragonboard (Android) and wolf
TEST=(Chrome OS)

Change-Id: Iac3b91300f938e8080d6ab4513fe84dea2880693
diff --git a/shill_manager.h b/shill_manager.h
index 4709795..dd0089b 100644
--- a/shill_manager.h
+++ b/shill_manager.h
@@ -21,20 +21,20 @@
 #include <string>
 
 #include <base/macros.h>
-#include <base/memory/ref_counted.h>
 #include <base/memory/weak_ptr.h>
-#include <dbus/bus.h>
 
 #include "apmanager/shill_proxy_interface.h"
 
 namespace apmanager {
 
+class ControlInterface;
+
 class ShillManager {
  public:
   ShillManager();
   virtual ~ShillManager();
 
-  void Init(const scoped_refptr<dbus::Bus>& bus);
+  void Init(ControlInterface* control_interface);
 
   // Claim the given interface |interface_name| from shill.
   virtual void ClaimInterface(const std::string& interface_name);