Use ScopedRefNPObject to pass NPObjects in the host plugin.

remoting/host/plugin/host_plugin_utils.h

Index: remoting/host/plugin/host_plugin_utils.h
diff --git a/remoting/host/plugin/host_plugin_utils.h b/remoting/host/plugin/host_plugin_utils.h
index b1e4c73c91bab5a85607120c146235bd36ef4959..46f05f6c25062a29cc872ecafca35bd66e205f89 100644
--- a/remoting/host/plugin/host_plugin_utils.h
+++ b/remoting/host/plugin/host_plugin_utils.h
@@ -36,18 +36,18 @@ class ScopedRefNPObject {
  public:
   ScopedRefNPObject();
   explicit ScopedRefNPObject(NPObject* object);
+  explicit ScopedRefNPObject(const ScopedRefNPObject& object);
   ~ScopedRefNPObject();
 
   // Release the held reference and replace it with |object|, incrementing
   // its reference count.
   ScopedRefNPObject& operator=(NPObject* object);
+  ScopedRefNPObject& operator=(const ScopedRefNPObject& object);
 
-  NPObject* get() { return object_; }
+  NPObject* get() const { return object_; }
 
  private:
   NPObject* object_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedRefNPObject);
 };
 
 }  // namespace remoting