[IndexedDB] Add Observer Tests

third_party/WebKit/LayoutTests/storage/indexeddb/resources/promise-idb.js

+// Quick and dirty promise wrapper of IDB.
+
+var pdb = {
+  _transformRequestToPromise: function(thisobj, func, argArray) {
+    return new Promise(function(resolve, reject) {
+      var request = func.apply(thisobj, argArray);
+      request.onsuccess = function() {
+        resolve(request.result);
+      };
+      request.onerror = reject;
+    })
+  },
+
+  transact: function(db, objectStores, style) {
+    return Promise.resolve(db.transaction(objectStores, style));
+  },
+
+  openCursor: function(txn, indexOrObjectStore, keyrange, callback) {
+    return new Promise(function(resolve, reject) {
+      var request = indexOrObjectStore.openCursor(keyrange);
+      request.onerror = reject;
+      request.onsuccess = function() {
+        var cursor = request.result;
+        var cont = false;
+        var control = {
+          continue: function() {cont = true;}
+        };
+        if (cursor) {
+          callback(control, cursor.value);
+          if (cont) {
+            cursor.continue();
+          } else {
+            resolve(txn);
+          }
+        } else {
+          resolve(txn);
+        }
+      };
+    });
+  },
+
+  get: function(indexOrObjectStore, key) {
+    return this._transformRequestToPromise(indexOrObjectStore, indexOrObjectStore.get, [key]);
+  },
+
+  count: function(indexOrObjectStore, key) {
+    return this._transformRequestToPromise(indexOrObjectStore, indexOrObjectStore.count, [key]);
+  },
+
+  put: function(objectStore, key, value) {
+    return this._transformRequestToPromise(objectStore, objectStore.put, [key, value]);
+  },
+
+  add: function(objectStore, key, value) {
+    return this._transformRequestToPromise(objectStore, objectStore.add, [key, value]);
+  },
+
+  delete: function(objectStore, key) {
+    return this._transformRequestToPromise(objectStore, objectStore.delete, [key]);
+  },
+
+  clear: function(objectStore) {
+    return this._transformRequestToPromise(objectStore, objectStore.clear, []);
+  },
+
+  getKey: function(index, key) {
+    return this._transformRequestToPromise(index, index.getKey, [key]);
+  },
+
+  waitForTransaction: function(txn) {
+    return new Promise(function(resolve, reject) {
+      txn.oncomplete = resolve;
+      txn.onerror = reject;
+      txn.onabort = reject;
+    });
+  }
+}