Check the context type in StopChromeTracing

tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_client_backend.py

 # Copyright 2014 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.
 
 import logging
 import re
 
 from telemetry import decorators
 from telemetry.timeline import trace_data as trace_data_module
 from telemetry.core.backends.chrome_inspector import devtools_http
@@ skipping 116 matching lines @@
                          those three event categories.
     """
     assert trace_options and trace_options.enable_chrome_trace
     self._CreateTracingBackendIfNeeded()
     return self._tracing_backend.StartTracing(
         trace_options, custom_categories, timeout)
 
   def StopChromeTracing(self, trace_data_builder, timeout=30):
     context_map = self.GetUpdatedInspectableContexts()
     for context in context_map.contexts:
+      if context['type'] not in ['iframe', 'page', 'webview']:
+        continue
       context_id = context['id']
       backend = context_map.GetInspectorBackend(context_id)
       success = backend.EvaluateJavaScript(
           "console.time('" + backend.id + "');" +
           "console.timeEnd('" + backend.id + "');" +
           "console.time.toString().indexOf('[native code]') != -1;")
       if not success:
         raise Exception('Page stomped on console.time')
       trace_data_builder.AddEventsTo(
           trace_data_module.TAB_ID_PART, [backend.id])
@@ skipping 53 matching lines @@
       # If an InspectorBackend is already created for the tab,
       # webSocketDebuggerUrl will be missing, and this is expected.
       context_id = context['id']
       if context_id not in self._inspector_backends_dict:
         if 'webSocketDebuggerUrl' not in context:
           logging.debug('webSocketDebuggerUrl missing, removing %s'
                         % context_id)
           continue
       valid_contexts.append(context)
     self._contexts = valid_contexts