Don't abort the MimeHandlerStreamManager stream if we receive a RenderProcessHostChanged notificati…

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 00421e74152c27c1b483120751a21f396e7ff891..e19900433e2f91b160c98eeae94a017132eb4611 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -308,6 +308,8 @@ WebContents* WebContents::FromRenderFrameHost(RenderFrameHost* rfh) {
 WebContents* WebContents::FromFrameTreeNodeId(int frame_tree_node_id) {
   FrameTreeNode* frame_tree_node =
       FrameTreeNode::GloballyFindByID(frame_tree_node_id);
+  if (!frame_tree_node)
+    return nullptr;
   return FromRenderFrameHost(frame_tree_node->current_frame_host());
 }