Pipeline: Invalidate weak pointers before returning stop callback.

media/base/pipeline.cc

Index: media/base/pipeline.cc
diff --git a/media/base/pipeline.cc b/media/base/pipeline.cc
index c1446828394c60a725fc2c33700d2270e7a5e05f..df3ddade7483e51d6f9d662fd92cdd47d532e5a1 100644
--- a/media/base/pipeline.cc
+++ b/media/base/pipeline.cc
@@ -602,7 +602,14 @@ void Pipeline::StopTask(const base::Closure& stop_cb) {
   DCHECK(stop_cb_.is_null());
 
   if (state_ == kStopped) {
+    // Invalid all weak pointers so it's safe to destroy |this| on the render
+    // main thread.
+    weak_factory_.InvalidateWeakPtrs();
+
+    // NOTE: pipeline may be deleted at this point in time as a result of
+    // executing |stop_cb|.
     stop_cb.Run();
+
     return;
   }