MD Bookmarks: Proof-of-concept reimplementation of data storage/binding layer

chrome/test/data/webui/md_bookmarks/test_store.js

Index: chrome/test/data/webui/md_bookmarks/test_store.js
diff --git a/chrome/test/data/webui/md_bookmarks/test_store.js b/chrome/test/data/webui/md_bookmarks/test_store.js
new file mode 100644
index 0000000000000000000000000000000000000000..28a1ee8591a17eeff50cbdc342dffbef613bd05d
--- /dev/null
+++ b/chrome/test/data/webui/md_bookmarks/test_store.js
@@ -0,0 +1,42 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+cr.define('bookmarks', function() {
+  var TestStore = function(data) {
+    this.data = Object.assign(bookmarks.util.createEmptyState(), data);
+    this.actions_ = [];
+    this.observers_ = [];
+  };
+
+  TestStore.prototype = {
+    addObserver: function(client) {
+      this.observers_.push(client);
+    },
+
+    removeObserver: function(client) {},
+
+    isInitialized: function() {
+      return true;
+    },
+
+    handleAction: function(action) {
+      this.actions_.push(action);
+    },
+
+    get lastAction() {
+      return this.actions_[this.actions_.length - 1];
+    },
+
+    notifyObservers: function() {
+      // For simplicity, we don't want tests to have to worry about modifying
+      // the whole state tree when they want to change a single property. An
+      // alternative is to perform a deep clone in here.
+      this.observers_.forEach((client) => client.onStateChanged(this.data));
+    },
+  };
+
+  return {
+    TestStore: TestStore,
+  };
+});