Fix resource leaks in CDM implementation.

ppapi/proxy/ppp_content_decryptor_private_proxy.cc

Index: ppapi/proxy/ppp_content_decryptor_private_proxy.cc
diff --git a/ppapi/proxy/ppp_content_decryptor_private_proxy.cc b/ppapi/proxy/ppp_content_decryptor_private_proxy.cc
index fe6a928a64f753b7242e40971a832670f0c2bb56..e03cf80c2e8589b4d723f6e2c19fe5f73d1fb70a 100644
--- a/ppapi/proxy/ppp_content_decryptor_private_proxy.cc
+++ b/ppapi/proxy/ppp_content_decryptor_private_proxy.cc
@@ -140,11 +140,6 @@ PP_Bool Decrypt(PP_Instance instance,
     return PP_FALSE;
   }
 
-  // We need to take a ref on the resource now. The browser may drop
-  // references once we return from here, but we're sending an asynchronous
-  // message. The plugin side takes ownership of that reference.
-  core->AddRefResource(encrypted_block);
-
   HostResource host_resource;
   host_resource.SetHostResource(instance, encrypted_block);