Browser+LibWeb+WebContent: Add ability to inspect local storage

The storage inspector now has a new tab for local storage. The next step
would be to persist local storage and receive real-time notifications
for changes to update the table view.

Userland/Applications/Browser/LocalStorageModel.cpp

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2022, Valtteri Koskivuori <vkoskiv@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "LocalStorageModel.h"
+
+namespace Browser {
+
+void LocalStorageModel::set_items(OrderedHashMap<String, String> map)
+{
+    begin_insert_rows({}, m_local_storage_entries.size(), m_local_storage_entries.size());
+    m_local_storage_entries = map;
+    end_insert_rows();
+
+    did_update(DontInvalidateIndices);
+}
+
+void LocalStorageModel::clear_items()
+{
+    begin_insert_rows({}, m_local_storage_entries.size(), m_local_storage_entries.size());
+    m_local_storage_entries.clear();
+    end_insert_rows();
+
+    did_update(DontInvalidateIndices);
+}
+
+String LocalStorageModel::column_name(int column) const
+{
+    switch (column) {
+    case Column::Key:
+        return "Key";
+    case Column::Value:
+        return "Value";
+    case Column::__Count:
+        return {};
+    }
+
+    return {};
+}
+
+GUI::ModelIndex LocalStorageModel::index(int row, int column, GUI::ModelIndex const&) const
+{
+    if (static_cast<size_t>(row) < m_local_storage_entries.size())
+        return create_index(row, column, NULL);
+    return {};
+}
+
+GUI::Variant LocalStorageModel::data(GUI::ModelIndex const& index, GUI::ModelRole role) const
+{
+    if (role != GUI::ModelRole::Display)
+        return {};
+
+    auto const& keys = m_local_storage_entries.keys();
+    auto const& local_storage_key = keys[index.row()];
+    auto const& local_storage_value = m_local_storage_entries.get(local_storage_key).value_or({});
+
+    switch (index.column()) {
+    case Column::Key:
+        return local_storage_key;
+    case Column::Value:
+        return local_storage_value;
+    }
+
+    VERIFY_NOT_REACHED();
+}
+
+}