Emit logcats from sandbox_linux_unittests.

sandbox/sandbox_linux_unittests_android.isolate

 # Copyright 2015 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.
 {
   'includes': [
     '../build/android/android.isolate',
     'sandbox_linux_unittests.isolate',
   ],
   'variables': {
     'command': [
       '<(PRODUCT_DIR)/bin/run_sandbox_linux_unittests',
+      '--logcat-output-dir', '${ISOLATED_OUTDIR}/logcats',
     ],
     'files': [
       '<(PRODUCT_DIR)/bin/run_sandbox_linux_unittests',
       '<(PRODUCT_DIR)/sandbox_linux_unittests',
     ]
   },
 }