1 files changed, 88 insertions, 0 deletions
diff --git a/browser/components/sessionstore/GlobalState.sys.mjs b/browser/components/sessionstore/GlobalState.sys.mjs
new file mode 100644
index 0000000000..a49fe4650d
--- /dev/null
+++ b/browser/components/sessionstore/GlobalState.sys.mjs
@@ -0,0 +1,88 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const EXPORTED_METHODS = [
+  "getState",
+  "clear",
+  "get",
+  "set",
+  "delete",
+  "setFromState",
+];
+
+/**
+ * Module that contains global session data.
+ */
+export function GlobalState() {
+  let internal = new GlobalStateInternal();
+  let external = {};
+  for (let method of EXPORTED_METHODS) {
+    external[method] = internal[method].bind(internal);
+  }
+  return Object.freeze(external);
+}
+
+function GlobalStateInternal() {
+  // Storage for global state.
+  this.state = {};
+}
+
+GlobalStateInternal.prototype = {
+  /**
+   * Get all value from the global state.
+   */
+  getState() {
+    return this.state;
+  },
+
+  /**
+   * Clear all currently stored global state.
+   */
+  clear() {
+    this.state = {};
+  },
+
+  /**
+   * Retrieve a value from the global state.
+   *
+   * @param aKey
+   *        A key the value is stored under.
+   * @return The value stored at aKey, or an empty string if no value is set.
+   */
+  get(aKey) {
+    return this.state[aKey] || "";
+  },
+
+  /**
+   * Set a global value.
+   *
+   * @param aKey
+   *        A key to store the value under.
+   */
+  set(aKey, aStringValue) {
+    this.state[aKey] = aStringValue;
+  },
+
+  /**
+   * Delete a global value.
+   *
+   * @param aKey
+   *        A key to delete the value for.
+   */
+  delete(aKey) {
+    delete this.state[aKey];
+  },
+
+  /**
+   * Set the current global state from a state object. Any previous global
+   * state will be removed, even if the new state does not contain a matching
+   * key.
+   *
+   * @param aState
+   *        A state object to extract global state from to be set.
+   */
+  setFromState(aState) {
+    this.state = (aState && aState.global) || {};
+  },
+};