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diff --git a/tools/page_cycler/database/common.js b/tools/page_cycler/database/common.js
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+// Copyright (c) 2006-2009 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.
+
+/**
+ * @fileoverview A collection of common functions used by all database
+ * performance tests.
+ */
+
+var CANNOT_OPEN_DB = -1;
+var SETUP_FAILED = -2;
+var TEST_FAILED = -3;
+
+var TRANSACTIONS = 1000;  // number of transactions; number of rows in the DB
+var RANDOM_STRING_LENGTH = 20;  // the length of the string on each row
+
+/**
+ * Generates a random string of upper-case letters of
+ * RANDOM_STRING_LENGTH length.
+ */
+function getRandomString() {
+  var s = '';
+  for (var i = 0; i < RANDOM_STRING_LENGTH; i++)
+    s += String.fromCharCode(Math.floor(Math.random() * 26) + 64);
+  return s;
+}
+
+/**
+ * Sets up and runs a performance test.
+ * @param {!Object} params An object which must have the following fields:
+ *   dbName: The database name.
+ *   readOnly: If true, transactions will be run using the readTransaction()
+ *       method. Otherwise, transaction() will be used.
+ *   insertRowsAtSetup: Determines if setting up the database should include
+ *       inserting TRANSACTIONS rows in it.
+ *   transactionCallback: The transaction callback that should be timed. This
+ *       function will be run TRANSACTIONS times and must take a transaction
+ *       object as its only parameter.
+ *   customRunTransactions: A custom function for running and timing
+ *       transactions. If this parameter is not null, runPerformanceTest() will
+ *       ignore the txFnct parameter and will call customRunTransactions() as
+ *       soon as the setup is complete. In this case, the user is responsible
+ *       for running and timing the transactions. If not null, this parameter
+ *       must be a function that takes a database object as its only parameter.
+ */
+function runPerformanceTest(params) {
+  var db = openTestDatabase(params.dbName);
+  if (!db) {
+    testComplete(CANNOT_OPEN_DB);
+    return;
+  }
+
+  db.transaction(
+      function(tx) {
+        tx.executeSql('CREATE TABLE Test (ID INT, Foo TEXT)', [],
+                      function(tx, data) {}, function(tx, error) {});
+        tx.executeSql('DELETE FROM Test');
+        if (params.insertRowsAtSetup) {
+          var randomString = getRandomString();
+          for (var i = 0; i < TRANSACTIONS; i++) {
+            tx.executeSql('INSERT INTO Test VALUES (?, ?)',
+                          [i, randomString]);
+          }
+        }
+      }, function(error) {
+        testComplete(SETUP_FAILED);
+      }, function() {
+        if (params.customRunTransactions)
+          params.customRunTransactions(db);
+        else
+          runTransactions(db, params.readOnly, params.transactionCallback);
+      });
+}
+
+/**
+ * Opens a database with the given name.
+ * @param {string} name The name of the database.
+ */
+function openTestDatabase(name) {
+  if (window.openDatabase) {
+    return window.openDatabase(name, '1.0', 'Test database.',
+                               TRANSACTIONS * RANDOM_STRING_LENGTH);
+  }
+
+  return null;
+}
+
+/**
+ * Runs the given transaction TRANSACTIONS times.
+ * @param {!Object} db The database to run transactions on.
+ * @param {boolean} readOnly If true, all transactions will be run using the
+ *     db.readTransaction() call. Otherwise, the transactions will be run
+ *     using the db.transaction() call.
+ * @param {function(!Object)} The transaction callback.
+ */
+function runTransactions(db, readOnly, transactionCallback) {
+  var transactionsCompleted = 0;
+  var transactionFunction = readOnly ? db.readTransaction : db.transaction;
+  var startTime = Date.now();
+  for (var i = 0; i < TRANSACTIONS; i++) {
+    transactionFunction.call(db, transactionCallback,
+                             function(error) {
+                               testComplete(TEST_FAILED);
+                             }, function() {
+                               if (++transactionsCompleted == TRANSACTIONS)
+                                 testComplete(Date.now() - startTime);
+                             });
+  }
+}