Add trace events for some of telemetry internal functions

telemetry/telemetry/internal/backends/chrome_inspector/inspector_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 functools
 import logging
 import os
 import socket
 import sys
 
+from py_trace_event import trace_event
+
 from telemetry.core import exceptions
 from telemetry import decorators
 from telemetry.internal.backends.chrome_inspector import devtools_http
 from telemetry.internal.backends.chrome_inspector import inspector_console
 from telemetry.internal.backends.chrome_inspector import inspector_memory
 from telemetry.internal.backends.chrome_inspector import inspector_page
 from telemetry.internal.backends.chrome_inspector import inspector_runtime
 from telemetry.internal.backends.chrome_inspector import inspector_websocket
 from telemetry.internal.backends.chrome_inspector import websocket
 
@@ skipping 15 matching lines @@
 
   return inner
 
 
 class InspectorBackend(object):
   """Class for communicating with a devtools client.
 
   The owner of an instance of this class is responsible for calling
   Disconnect() before disposing of the instance.
   """
+
+  __metaclass__ = trace_event.TracedMetaClass
+
   def __init__(self, app, devtools_client, context, timeout=120):
     self._websocket = inspector_websocket.InspectorWebsocket()
     self._websocket.RegisterDomain(
         'Inspector', self._HandleInspectorDomainNotification)
 
     self._app = app
     self._devtools_client = devtools_client
     # Be careful when using the context object, since the data may be
     # outdated since this is never updated once InspectorBackend is
     # created. Consider an updating strategy for this. (For an example
@@ skipping 350 matching lines @@
       msg = (
           'Received a socket error in the browser connection and the tab no '
           'longer exists. The tab probably crashed.'
       )
     error.AddDebuggingMessage(msg)
     error.AddDebuggingMessage('Debugger url: %s' % self.debugger_url)
 
   @_HandleInspectorWebSocketExceptions
   def CollectGarbage(self):
     self._page.CollectGarbage()