Allow dbus clients to silence logging when a service is unavailable.

dbus/object_proxy.h

Index: dbus/object_proxy.h
diff --git a/dbus/object_proxy.h b/dbus/object_proxy.h
index ef453054915786accb66d82268a22506b6a69240..e9135f2d0e799c564b99d7e7a3d00598e532cc40 100644
--- a/dbus/object_proxy.h
+++ b/dbus/object_proxy.h
@@ -30,11 +30,20 @@ class Signal;
 // object is is alive when callbacks referencing |this| are called.
 class ObjectProxy : public base::RefCountedThreadSafe<ObjectProxy> {
  public:
-  // Client code should use Bus::GetObjectProxy() instead of this
-  // constructor.
+  // Client code should use Bus::GetObjectProxy() or
+  // Bus::GetObjectProxyWithOptions() instead of this constructor.
   ObjectProxy(Bus* bus,
               const std::string& service_name,
-              const std::string& object_path);
+              const std::string& object_path,
+              int options);
+
+  // Options to be OR-ed together when calling Bus::GetObjectProxyWithOptions().
+  // Set the IGNORE_SERVICE_UNKNOWN_ERRORS option to silence logging of
+  // org.freedesktop.DBus.Error.ServiceUnknown errors.
+  enum Options {
+    DEFAULT_OPTIONS = 0,
+    IGNORE_SERVICE_UNKNOWN_ERRORS = 1 << 0
+  };
 
   // Special timeout constants.
   //
@@ -194,6 +203,8 @@ class ObjectProxy : public base::RefCountedThreadSafe<ObjectProxy> {
 
   std::set<std::string> match_rules_;
 
+  const bool log_unknown_service_errors_;
+
   DISALLOW_COPY_AND_ASSIGN(ObjectProxy);
 };