Fix null heap profiler tag for allocations

mojo/public/cpp/bindings/lib/connector.cc

Index: mojo/public/cpp/bindings/lib/connector.cc
diff --git a/mojo/public/cpp/bindings/lib/connector.cc b/mojo/public/cpp/bindings/lib/connector.cc
index 433e45e5825000145c175343cc2dee97a708404b..7053915172d72a544bb7db9e67d8d56a7e24c5b3 100644
--- a/mojo/public/cpp/bindings/lib/connector.cc
+++ b/mojo/public/cpp/bindings/lib/connector.cc
@@ -218,7 +218,8 @@ void Connector::WaitToReadMore() {
   DCHECK(!handle_watcher_);
 
   handle_watcher_.reset(new Watcher(FROM_HERE, task_runner_));
-  handle_watcher_->set_heap_profiler_tag(heap_profiler_tag_);
+  if (heap_profiler_tag_)
+    handle_watcher_->set_heap_profiler_tag(heap_profiler_tag_);
   MojoResult rv = handle_watcher_->Start(
       message_pipe_.get(), MOJO_HANDLE_SIGNAL_READABLE,
       base::Bind(&Connector::OnWatcherHandleReady, base::Unretained(this)));