Cashew: implement backend usage API

src/cashew_server.h

Index: src/cashew_server.h
diff --git a/src/cashew_server.h b/src/cashew_server.h
index cf5a4e63d56ce806166c18e4cd514f3f33a617cb..09d1d532a901c58bb010aed967a570a0851905db 100644
--- a/src/cashew_server.h
+++ b/src/cashew_server.h
@@ -15,17 +15,18 @@
 #include "src/cashew_server_glue.h"
 #include "src/data_plan.h"
 #include "src/service.h"
-#include "src/service_manager.h"
 
 namespace cashew {
 
+class ServiceManager;
+
 // Implements Cashew D-Bus API
 class CashewServer : public org::chromium::Cashew_adaptor,
                      public DBus::IntrospectableAdaptor,
                      public DBus::ObjectAdaptor {
   public:
     CashewServer(DBus::Connection& connection,  // NOLINT
-                 const ServiceManager& service_manager);
+                 ServiceManager * const service_manager);
     virtual ~CashewServer();
 
     // Cashew D-Bus API methods
@@ -44,10 +45,15 @@ class CashewServer : public org::chromium::Cashew_adaptor,
     static const char* kServiceName;
     static const char* kServicePath;
 
+    // Service Manager methods
+
+    // Service Manager wants us to emit an update for a Service
+    virtual void EmitDataPlansUpdate(const Service& service);
+
   private:
-    const ServiceManager& service_manager_;
+    ServiceManager * const service_manager_;
 
-    // Emit a DataPlansUpdate signal for a service
+    // Emit a DataPlansUpdate D-Bus signal for a service
     void EmitDataPlansUpdateSignal(const Service& service);
 
     DISALLOW_COPY_AND_ASSIGN(CashewServer);