Clean up some old TODOs

chrome/renderer/renderer_webidbindex_impl.cc

Index: chrome/renderer/renderer_webidbindex_impl.cc
diff --git a/chrome/renderer/renderer_webidbindex_impl.cc b/chrome/renderer/renderer_webidbindex_impl.cc
index 12e990f60bd02dfde9f145bc0be6e340ad20e454..acbe6cbc27d76f95896548c7309b712d1ca44e03 100644
--- a/chrome/renderer/renderer_webidbindex_impl.cc
+++ b/chrome/renderer/renderer_webidbindex_impl.cc
@@ -21,8 +21,10 @@ RendererWebIDBIndexImpl::RendererWebIDBIndexImpl(int32 idb_index_id)
 }
 
 RendererWebIDBIndexImpl::~RendererWebIDBIndexImpl() {
-  // TODO(jorlow): Is it possible for this to be destroyed but still have
-  //               pending callbacks?  If so, fix!
+  // It's not possible for there to be pending callbacks that address this
+  // object since inside WebKit, they hold a reference to the object wich owns
+  // this object. But, if that ever changed, then we'd need to invalidate
+  // any such pointers.
   RenderThread::current()->Send(new IndexedDBHostMsg_IndexDestroyed(
       idb_index_id_));
 }