refactor: ginify Tray (#22822)

* refactor: ginify Tray

* lint

* improve argument parsing logic

* remove redundant imports from tray.js

* new Tray produces an instanceof Tray

* make Constructible generic

* lint

* clean up on exit

shell/common/gin_helper/cleaned_up_at_exit.cc

@@ -0,0 +1,33 @@
+// Copyright (c) 2020 Slack Technologies, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#include "shell/common/gin_helper/cleaned_up_at_exit.h"
+
+#include "base/containers/flat_set.h"
+#include "base/no_destructor.h"
+
+namespace gin_helper {
+
+base::flat_set<CleanedUpAtExit*>& GetDoomed() {
+  static base::NoDestructor<base::flat_set<CleanedUpAtExit*>> doomed;
+  return *doomed;
+}
+CleanedUpAtExit::CleanedUpAtExit() {
+  GetDoomed().insert(this);
+}
+CleanedUpAtExit::~CleanedUpAtExit() {
+  GetDoomed().erase(this);
+}
+
+// static
+void CleanedUpAtExit::DoCleanup() {
+  auto& doomed = GetDoomed();
+  while (!doomed.empty()) {
+    auto iter = doomed.begin();
+    delete *iter;
+    // It removed itself from the list.
+  }
+}
+
+}  // namespace gin_helper