Check the context type in StopChromeTracing

tools/telemetry/telemetry/core/platform/tracing_controller_unittest.py

+# Copyright 2015 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.core.platform import tracing_category_filter
+from telemetry.core.platform import tracing_options
+from telemetry.unittest_util import tab_test_case
+
+class TracingControllerTest(tab_test_case.TabTestCase):
+  # Disabled due to http://crbug.com/459807
+  @decorators.Disabled
+  @decorators.Isolated
+  def testModifiedConsoleTime(self):
+    category_filter = tracing_category_filter.TracingCategoryFilter()
+    options = tracing_options.TracingOptions()
+    options.enable_chrome_trace = True
+    self._tab.browser.platform.tracing_controller.Start(options,
+                                                        category_filter)
+    self.Navigate('blank.html')
+    self.assertEquals(
+        self._tab.EvaluateJavaScript('document.location.pathname;'),
+        '/blank.html')
+    self._tab.EvaluateJavaScript('console.time = function() { };')
+    with self.assertRaisesRegexp(Exception, 'Page stomped on console.time'):
+      self._tab.browser.platform.tracing_controller.Stop()