Revert "Enable logcat logging for adb_host."

This reverts commit f21ef531bc634830a043d6b09e2976b571b56a71.

The reason is in the comment of patchset 9

Change-Id: If0b463e6d2d4b3d48b0454195a1c6eabde9b1b59
Reviewed-on: https://chromium-review.googlesource.com/348030
Reviewed-by: Dan Shi <dshi@google.com>
Commit-Queue: Dan Shi <dshi@google.com>
Tested-by: Dan Shi <dshi@google.com>
diff --git a/server/hosts/adb_host.py b/server/hosts/adb_host.py
index b4ea0ca..282d3d4 100644
--- a/server/hosts/adb_host.py
+++ b/server/hosts/adb_host.py
@@ -1,7 +1,6 @@
 # Copyright (c) 2013 The Chromium OS 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 datetime
 import functools
 import logging
 import os
@@ -56,8 +55,6 @@
                     CMD_OUTPUT_PREFIX)
 RELEASE_FILE = 'ro.build.version.release'
 BOARD_FILE = 'ro.product.device'
-SDK_FILE = 'ro.build.version.sdk'
-LOGCAT_FILE = 'logcat.log'
 TMP_DIR = '/data/local/tmp'
 # Regex to pull out file type, perms and symlink. Example:
 # lrwxrwx--- 1 6 root system 2015-09-12 19:21 blah_link -> ./blah
@@ -401,14 +398,11 @@
 
 
     def job_start(self):
-        """Overload of parent which intentionally doesn't log certain files.
-
-        The parent implementation attempts to log certain Linux files, such as
-        /var/log, which do not exist on Android, thus there is no call to the
-        parent's job_start().  The sync call is made so that logcat logs can be
-        approximately matched to server logs.
         """
-        self._sync_time()
+        Disable log collection on adb_hosts.
+
+        TODO(sbasi): crbug.com/305427
+        """
 
 
     def run(self, command, timeout=3600, ignore_status=False,
@@ -682,18 +676,6 @@
         return bool(devices and (not serial or serial in devices))
 
 
-    def stop_loggers(self):
-        """Inherited stop_loggers function.
-
-        Calls parent function and captures logcat, since the end of the run
-        is logically the end/stop of the logcat log.
-        """
-        super(ADBHost, self).stop_loggers()
-        # Record the logcat file.
-        logcat_logfilename = os.path.join(self.job.resultdir, LOGCAT_FILE)
-        self.adb_run('logcat -v time -d > "%s"' % (logcat_logfilename))
-
-
     def close(self):
         """Close the ADBHost object.
 
@@ -1589,22 +1571,3 @@
                                          'build_id': build_id})
         return '%s/static/%s/%s' % (ds.url(), image,
                                     autotest_server_package_name)
-
-
-    def _sync_time(self):
-        """Approximate synchronization of time between host and ADB device.
-
-        This sets the ADB/Android device's clock to approximately the same
-        time as the Autotest host for the purposes of comparing Android system
-        logs such as logcat to logs from the Autotest host system.
-        """
-        command = 'date '
-        sdk_version = int(self.run('getprop %s' % SDK_FILE).stdout)
-        if sdk_version < 23:
-            # Android L and earlier use this format: date -s (format).
-            command += ('-s %s' %
-                        datetime.datetime.now().strftime('%Y%m%d.%H%M%S'))
-        else:
-            # Android M and later use this format: date (format).
-            command += datetime.datetime.now().strftime('%m%d%H%M%Y.%S')
-        self.run(command)