[Telemetry] Refactor Chrome devtools tracing

tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_backend.py

Index: tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_backend.py
diff --git a/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_backend.py b/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_backend.py
deleted file mode 100644
index b1345ad91e5d5f973e2c1a025e19b5b8f2877fab..0000000000000000000000000000000000000000
--- a/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_backend.py
+++ /dev/null
@@ -1,114 +0,0 @@
-# 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 sys
-import traceback
-
-
-class ChromeTracingStartedError(Exception):
-  pass
-
-
-class ChromeTracingStoppedError(Exception):
-  pass
-
-
-class ChromeDevtoolsTracingBackend(object):
-  # A singleton map from platform backends to maps of uniquely-identifying
-  # remote port (which may be the same as local port) to DevToolsClientBackend.
-  # There is no guarantee that the devtools agent is still alive.
-  _platform_backends_to_devtools_clients_maps = {}
-  _is_tracing_running_for_platform_backend = {}
-  _is_tracing_running_for_platform_backend.setdefault(False)
-
-  def __init__(self, platform_backend):
-    self._platform_backend = platform_backend
-
-  @classmethod
-  def _RemoveStaleDevToolsClient(cls, platform_backend):
-    """Removes DevTools clients that are no longer connectable."""
-    devtools_clients_map = cls._platform_backends_to_devtools_clients_maps.get(
-        platform_backend, {})
-    devtools_clients_map = {
-        port: client
-        for port, client in devtools_clients_map.iteritems()
-        if client.IsAlive()
-        }
-    cls._platform_backends_to_devtools_clients_maps[platform_backend] = (
-        devtools_clients_map)
-
-  @classmethod
-  def RegisterDevToolsClient(cls, devtools_client_backend, platform_backend):
-    is_tracing_running = cls._is_tracing_running_for_platform_backend.get(
-        platform_backend)
-    if is_tracing_running:
-      raise ChromeTracingStartedError(
-          'Cannot add new DevTools client when tracing is running on '
-          'platform backend %s.' % platform_backend)
-    remote_port = str(devtools_client_backend.remote_port)
-    if platform_backend not in cls._platform_backends_to_devtools_clients_maps:
-      cls._platform_backends_to_devtools_clients_maps[platform_backend] = {}
-    devtools_clients_map = (
-      cls._platform_backends_to_devtools_clients_maps[platform_backend])
-    devtools_clients_map[remote_port] = devtools_client_backend
-
-  @classmethod
-  def IsSupported(cls, platform_backend):
-    cls._RemoveStaleDevToolsClient(platform_backend)
-    devtools_clients_map = cls._platform_backends_to_devtools_clients_maps.get(
-        platform_backend, {})
-    for _, devtools_client in devtools_clients_map.iteritems():
-      if devtools_client.IsChromeTracingSupported():
-        return True
-    return False
-
-  @property
-  def _is_active(self):
-    return self._is_tracing_running_for_platform_backend.get(
-        self._platform_backend)
-
-  @_is_active.setter
-  def _is_active(self, value):
-    self._is_tracing_running_for_platform_backend[self._platform_backend] = (
-        value)
-
-  def Start(self, trace_options, category_filter, timeout):
-    if not trace_options.enable_chrome_trace:
-      return False
-
-    if self._is_active:
-      raise ChromeTracingStartedError(
-          'Tracing is already running on platform backend %s.'
-          % self._platform_backend)
-    self._RemoveStaleDevToolsClient(self._platform_backend)
-    devtools_clients_map = self._platform_backends_to_devtools_clients_maps.get(
-        self._platform_backend, {})
-    if not devtools_clients_map:
-      return False
-    for _, devtools_client in devtools_clients_map.iteritems():
-      devtools_client.StartChromeTracing(
-          trace_options, category_filter.filter_string, timeout)
-    self._is_active = True
-    return True
-
-  def Stop(self, trace_data_builder):
-    devtools_clients_map = (
-      self._platform_backends_to_devtools_clients_maps[self._platform_backend])
-    raised_execption_messages = []
-    for devtools_port, devtools_client in devtools_clients_map.iteritems():
-      # We do not check for stale DevTools client, so that we get an
-      # exception if there is a stale client. This is because we
-      # will potentially lose data if there is a stale client.
-      try:
-        devtools_client.StopChromeTracing(trace_data_builder)
-      except Exception:
-        raised_execption_messages.append(
-          'Error when trying to stop tracing on devtools at port %s:\n%s'
-          % (devtools_port,
-             ''.join(traceback.format_exception(*sys.exc_info()))))
-
-    self._is_active = False
-    if raised_execption_messages:
-      raise ChromeTracingStoppedError(
-          'Exceptions raised when trying to stop devtool tracing\n:' +
-          '\n'.join(raised_execption_messages))