[Fuchsia] Remove loglistener from DeviceTarget.

Logs are already handled via SystemLogReader.

Bug: 1067356
Change-Id: Ide3a2d5545e1e8cdbd302be184612699ad149a86
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2347051
Commit-Queue: Chong Gu <chonggu@google.com>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796526}

build/fuchsia/device_target.py

@@ -84,7 +84,6 @@ class DeviceTarget(target.Target):
 
     self._port = port if port else 22
     self._system_log_file = system_log_file
-    self._loglistener = None
     self._host = host
     self._fuchsia_out_dir = os.path.expanduser(fuchsia_out_dir)
     self._node_name = node_name
@@ -113,10 +112,6 @@ class DeviceTarget(target.Target):
       boot_data.ProvisionSSH(output_dir)
       self._ssh_config_path = boot_data.GetSSHConfigPath(output_dir)
 
-  def __exit__(self, exc_type, exc_val, exc_tb):
-    if self._loglistener:
-      self._loglistener.kill()
-
   def _SDKHashMatches(self):
     """Checks if /data/.hash on the device matches SDK_ROOT/.hash.
 
@@ -269,14 +264,6 @@ class DeviceTarget(target.Target):
     self._node_name = m.groupdict()['nodename']
     logging.info('Booted device "%s".' % self._node_name)
 
-    # Start loglistener to save system logs.
-    if self._system_log_file:
-      loglistener_path = GetHostToolPathFromPlatform('loglistener')
-      self._loglistener = subprocess.Popen(
-          [loglistener_path, self._node_name],
-          stdout=self._system_log_file,
-          stderr=subprocess.STDOUT, stdin=open(os.devnull))
-
     # Repeatdly query mDNS until we find the device, or we hit the timeout of
     # DISCOVERY_TIMEOUT_SECS.
     logging.info('Waiting for device to join network.')