Make the adb logcat print out all usefull logcat.

Previously, for tags that are unknown, we will include the logcat only
when its priority level is e(error). This condition makes us lose a lot of
usefull logcat, because the condition basically means we do not include
logcat by default. It was a whitelist only.

In this cl, I am removing this condition. Thus for all tags that are
unknown, we will include the logcat no matter what its priority level
is. This way we will make sure that no important logcats are lost, and
will include logcat by default.

In the future, if we find that we have included too many logcats and
want to blacklist a tag, we can simply add <tag>:S into the
LOGCAT_FILTERS to blacklist the logcat with that tag.

Bug: 766743
Change-Id: I970a646a65b06fb66009a90c9a49df122c74d31d
Reviewed-on: https://chromium-review.googlesource.com/680894Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Zhiling Huang <hzl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504149}

build/android/pylib/local/device/local_device_environment.py

@@ -31,7 +31,6 @@ from py_utils import contextlib_ext
 
 
 LOGCAT_FILTERS = [
-  '*:e',
   'chromium:v',
   'cr_*:v',
   'DEBUG:I',