Add a handle validity check before getting pid.

Change-Id: Icbfecced7e68f62c7f9eca0623ddf35a9a241c24
Reviewed-on: https://chromium-review.googlesource.com/1053960Reviewed-by: Siddhartha S <ssid@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558131}

chrome/browser/ui/webui/memory_internals_ui.cc

@@ -326,12 +326,14 @@ void MemoryInternalsDOMHandler::ReturnProcessListOnUIThread(
   // Append renderer processes.
   auto iter = content::RenderProcessHost::AllHostsIterator();
   while (!iter.IsAtEnd()) {
+    if (iter.GetCurrentValue()->GetProcess().IsValid()) {
       base::ProcessId renderer_pid = iter.GetCurrentValue()->GetProcess().Pid();
       if (renderer_pid != 0) {
         // TODO(brettw) make a better description of the process, maybe see
         // what TaskManager does to get the page title.
         process_list.push_back(MakeProcessInfo(renderer_pid, "Renderer"));
       }
+    }
     iter.Advance();
   }