MultibufferDataSource: Handle HasSingleOrigin() before init completes.

media/blink/multibuffer_data_source.cc

Index: media/blink/multibuffer_data_source.cc
diff --git a/media/blink/multibuffer_data_source.cc b/media/blink/multibuffer_data_source.cc
index 9c776f5b3f8e35c0c2851efa4b81286eff79b914..a343fee303aef91f428fcad47dcf86f04ba6b61a 100644
--- a/media/blink/multibuffer_data_source.cc
+++ b/media/blink/multibuffer_data_source.cc
@@ -248,8 +248,8 @@ void MultibufferDataSource::SetBufferingStrategy(
 
 bool MultibufferDataSource::HasSingleOrigin() {
   DCHECK(render_task_runner_->BelongsToCurrentThread());
-  DCHECK(init_cb_.is_null() && reader_.get())
-      << "Initialize() must complete before calling HasSingleOrigin()";
+  // Before initialization completes there is no risk of leaking data. Callers
+  // are required to order checks such that this isn't a race.
   return single_origin_;
 }