LibWeb: Introduce RemoteBrowsingContext

Remote browsing context represents top level browsing context that
lives in another WebContent process.

Userland/Libraries/LibWeb/HTML/RemoteBrowsingContext.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2023, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/Bindings/MainThreadVM.h>
+#include <LibWeb/HTML/AbstractBrowsingContext.h>
+
+namespace Web::HTML {
+
+class RemoteBrowsingContext final
+    : public AbstractBrowsingContext
+    , public Weakable<RemoteBrowsingContext> {
+    JS_CELL(RemoteBrowsingContext, AbstractBrowsingContext);
+
+public:
+    static JS::NonnullGCPtr<RemoteBrowsingContext> create_a_new_remote_browsing_context(String handle);
+
+    virtual HTML::WindowProxy* window_proxy() override;
+    virtual HTML::WindowProxy const* window_proxy() const override;
+
+    virtual WebIDL::ExceptionOr<void> navigate(
+        JS::NonnullGCPtr<Fetch::Infrastructure::Request>,
+        BrowsingContext&,
+        bool,
+        HistoryHandlingBehavior,
+        Optional<PolicyContainer>,
+        DeprecatedString,
+        Optional<DeprecatedString>,
+        Function<void(JS::NonnullGCPtr<Fetch::Infrastructure::Response>)>) override
+    {
+        return {};
+    };
+
+    virtual String const& window_handle() const override { return m_window_handle; }
+    virtual void set_window_handle(String handle) override { m_window_handle = handle; };
+
+private:
+    explicit RemoteBrowsingContext(String);
+
+    String m_window_handle;
+};
+
+}