[tools/perf] Add integration test for about://tracing UI

tools/perf/core/about_tracing_integration_test.py

+# Copyright 2016 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.
+from telemetry import decorators
+from telemetry.testing import tab_test_case
+
+
+class AboutTracingIntegrationTest(tab_test_case.TabTestCase):
+
+  @decorators.Disabled('android',
+                       'win')  # crbug.com/630030
+  def testBasicTraceRecording(self):
+    action_runner = self._tab.action_runner
+    action_runner.Navigate('chrome://tracing')
+
+    # Click 'record' to trigger record selection diaglog.
+    action_runner.WaitForElement(selector='#record-button')
+    action_runner.ClickElement(selector='#record-button')
+
+    # Wait for record selection diaglog to pop up, then click record.
+    action_runner.WaitForElement(selector='.overlay')
+    action_runner.ClickElement(
+        element_function=("document.querySelector('.overlay').shadowRoot."
+                          "querySelectorAll('button')[0]"))
+
+    # Stop recording after 1 seconds.
+    action_runner.Wait(1)
+    action_runner.ClickElement(
+        element_function=
+        "document.querySelector('.overlay').querySelector('button')")
+
+    # Make sure that we can see the browser track.
+    action_runner.WaitForElement(selector='div[title~="Browser"]')