[Autotest][PY3] Migrating client/cros (kernel_trace -> rtc)

Migrating client/cros from kernel_trace.py -> rtc.py to python3.

BUG=chromium:990593
TEST= py_compile in py2 and py3. CQ. dummy_Pass. policy_ and network_
test

Change-Id: I8cd48c1ab6d0d71f6fcf2573fda6a5badda957b9
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2488642
Reviewed-by: Seewai Fu <seewaifu@google.com>
Reviewed-by: Greg Edelston <gredelston@google.com>
Commit-Queue: Derek Beckett <dbeckett@chromium.org>
Tested-by: Derek Beckett <dbeckett@chromium.org>
diff --git a/client/cros/kernel_trace.py b/client/cros/kernel_trace.py
index d901e55..264cffc 100644
--- a/client/cros/kernel_trace.py
+++ b/client/cros/kernel_trace.py
@@ -167,7 +167,7 @@
 
         fname = os.path.join(self._TRACE_ROOT, 'buffer_size_kb')
         result = utils.read_one_line(fname).strip()
-        if result is '0':
+        if result == '0':
             return True
         return False