Encrypted Media: Allows empty key message to be fired.

ppapi/proxy/ppb_instance_proxy.cc

Index: ppapi/proxy/ppb_instance_proxy.cc
diff --git a/ppapi/proxy/ppb_instance_proxy.cc b/ppapi/proxy/ppb_instance_proxy.cc
index 9c69bbd30fc9701fa1443f6487fcd18823758332..fccab295caea96edb43f5e42fd233dd049ab1fa5 100644
--- a/ppapi/proxy/ppb_instance_proxy.cc
+++ b/ppapi/proxy/ppb_instance_proxy.cc
@@ -540,17 +540,22 @@ void PPB_Instance_Proxy::KeyMessage(PP_Instance instance,
                                     PP_Var session_id,
                                     PP_Resource message,
                                     PP_Var default_url) {
-  Resource* object =
-      PpapiGlobals::Get()->GetResourceTracker()->GetResource(message);
-  if (!object || object->pp_instance() != instance)
-    return;
+  PP_Resource host_resource = 0;
+  if (message) {
+    Resource* object =
+        PpapiGlobals::Get()->GetResourceTracker()->GetResource(message);
+    if (!object || object->pp_instance() != instance)
+      return;
+    host_resource = object->host_resource().host_resource();
+  }
+
   dispatcher()->Send(
       new PpapiHostMsg_PPBInstance_KeyMessage(
           API_ID_PPB_INSTANCE,
           instance,
           SerializedVarSendInput(dispatcher(), key_system),
           SerializedVarSendInput(dispatcher(), session_id),
-          object->host_resource().host_resource(),
+          host_resource,
           SerializedVarSendInput(dispatcher(), default_url)));
 }