Add a method to check if a D-Bus service has an owner. Use it for mtpd.

dbus/object_proxy.h

Index: dbus/object_proxy.h
===================================================================
--- dbus/object_proxy.h	(revision 197157)
+++ dbus/object_proxy.h	(working copy)
@@ -64,13 +64,13 @@
 
   // Called when an error response is returned or no response is returned.
   // Used for CallMethodWithErrorCallback().
-  typedef base::Callback<void(ErrorResponse*)> ErrorCallback;
+  typedef base::Callback<void(ErrorResponse* error_response)> ErrorCallback;
 
   // Called when the response is returned. Used for CallMethod().
-  typedef base::Callback<void(Response*)> ResponseCallback;
+  typedef base::Callback<void(Response* response)> ResponseCallback;
 
   // Called when a signal is received. Signal* is the incoming signal.
-  typedef base::Callback<void (Signal*)> SignalCallback;
+  typedef base::Callback<void (Signal* signal)> SignalCallback;
 
   // Called when the object proxy is connected to the signal.
   // Parameters:
@@ -153,6 +153,13 @@
   // BLOCKING CALL.
   virtual void Detach();
 
+  // Convenient form of CallMethodAndBlock() to call
+  // org.freedesktop.DBus.GetNameOwner for the given |service_name|.
+  // Returns true if |service_name| has an owner.
+  //
+  // BLOCKING CALL.
+  static bool ServiceHasOwner(dbus::Bus* bus, const std::string& service_name);

[satorux1, 2013/04/30 01:53:10]

Looks rather awkward to have this in ObjectProxy as a static member function.
Maybe move this to bus.h as a non-static member function?

+
   // Returns an empty callback that does nothing. Can be used for
   // CallMethod().
   static ResponseCallback EmptyResponseCallback();