fix: disable contextBridge object identity caching (#21803)

* fix: disable contextBridge object identity caching

* cleanup

* chore: make non-const references raw pointers

* fix: zero-param constructors are not explicit

* refactor: use base::LinkedList

Co-authored-by: Jeremy Apthorp <nornagon@nornagon.net>

shell/renderer/api/context_bridge/object_cache.h

@@ -0,0 +1,53 @@
+// 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.
+
+#ifndef SHELL_RENDERER_API_CONTEXT_BRIDGE_OBJECT_CACHE_H_
+#define SHELL_RENDERER_API_CONTEXT_BRIDGE_OBJECT_CACHE_H_
+
+#include <map>
+#include <utility>
+
+#include "base/containers/linked_list.h"
+#include "content/public/renderer/render_frame.h"
+#include "content/public/renderer/render_frame_observer.h"
+#include "shell/renderer/electron_render_frame_observer.h"
+#include "third_party/blink/public/web/web_local_frame.h"
+
+namespace electron {
+
+namespace api {
+
+namespace context_bridge {
+
+using ObjectCachePair = std::pair<v8::Local<v8::Value>, v8::Local<v8::Value>>;
+
+struct ObjectCachePairNode : public base::LinkNode<ObjectCachePairNode> {
+  explicit ObjectCachePairNode(ObjectCachePair&& pair);
+  ~ObjectCachePairNode();
+
+  ObjectCachePair pair;
+};
+
+class ObjectCache final {
+ public:
+  ObjectCache();
+  ~ObjectCache();
+
+  void CacheProxiedObject(v8::Local<v8::Value> from,
+                          v8::Local<v8::Value> proxy_value);
+  v8::MaybeLocal<v8::Value> GetCachedProxiedObject(
+      v8::Local<v8::Value> from) const;
+
+ private:
+  // object_identity ==> [from_value, proxy_value]
+  std::map<int, base::LinkedList<ObjectCachePairNode>> proxy_map_;
+};
+
+}  // namespace context_bridge
+
+}  // namespace api
+
+}  // namespace electron
+
+#endif  // SHELL_RENDERER_API_CONTEXT_BRIDGE_OBJECT_CACHE_H_