Expose AppUi from devil utils in browser

telemetry/telemetry/internal/backends/browser_backend.py

 # Copyright 2013 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 uuid
 import sys
 
 from py_utils import cloud_storage  # pylint: disable=import-error
 
 from telemetry import decorators
 from telemetry.internal.backends import app_backend
@@ skipping 77 matching lines @@
   @property
   @decorators.Cache
   def tab_list_backend(self):
     return self._tab_list_backend_class(self)
 
   @property
   def supports_tracing(self):
     raise NotImplementedError()
 
   @property
+  def supports_app_ui_interactions(self):
+    return False
+
+  @property
   def supports_system_info(self):
     return False
 
   def StartTracing(self, trace_options,
                    timeout=web_contents.DEFAULT_WEB_CONTENTS_TIMEOUT):
     raise NotImplementedError()
 
   def StopTracing(self):
     raise NotImplementedError()
 
@@ skipping 53 matching lines @@
   def supports_cpu_metrics(self):
     raise NotImplementedError()
 
   @property
   def supports_memory_metrics(self):
     raise NotImplementedError()
 
   @property
   def supports_power_metrics(self):
     raise NotImplementedError()