[Autotest] Fix gtest regexs for PY3

These gives off warnings in py3, making them raw (r'') strings seems to
be a valid fix

BUG=chromium:990593
TEST=infra_ServerPythonVersion.2/3 (with py3 flags allowing), no
warnings shown from this module

Change-Id: I44092b4f87f4e59a23d7fdfb9f832a9694208af4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2946842
Commit-Queue: Derek Beckett <dbeckett@chromium.org>
Commit-Queue: Greg Edelston <gredelston@google.com>
Tested-by: Derek Beckett <dbeckett@chromium.org>
Auto-Submit: Derek Beckett <dbeckett@chromium.org>
Reviewed-by: Greg Edelston <gredelston@google.com>
diff --git a/client/common_lib/gtest_parser.py b/client/common_lib/gtest_parser.py
index 167e7e8..7bfdf32 100644
--- a/client/common_lib/gtest_parser.py
+++ b/client/common_lib/gtest_parser.py
@@ -47,21 +47,21 @@
         # This regexp also matches SomeName.SomeTest/1, which should be
         # harmless.
         test_name_regexp = r'((\w+/)?\w+\.\w+(\.\w+)?(/\d+)?)'
-        self._test_start = re.compile('\[\s+RUN\s+\] ' + test_name_regexp)
-        self._test_ok = re.compile('\[\s+OK\s+\] ' + test_name_regexp)
-        self._test_fail = re.compile('\[\s+FAILED\s+\] ' + test_name_regexp)
+        self._test_start = re.compile(r'\[\s+RUN\s+\] ' + test_name_regexp)
+        self._test_ok = re.compile(r'\[\s+OK\s+\] ' + test_name_regexp)
+        self._test_fail = re.compile(r'\[\s+FAILED\s+\] ' + test_name_regexp)
         self._test_timeout = re.compile(
-            'Test timeout \([0-9]+ ms\) exceeded for ' + test_name_regexp)
-        self._disabled = re.compile('  YOU HAVE (\d+) DISABLED TEST')
-        self._flaky = re.compile('  YOU HAVE (\d+) FLAKY TEST')
+                r'Test timeout \([0-9]+ ms\) exceeded for ' + test_name_regexp)
+        self._disabled = re.compile(r'  YOU HAVE (\d+) DISABLED TEST')
+        self._flaky = re.compile(r'  YOU HAVE (\d+) FLAKY TEST')
 
         self._suppression_start = re.compile(
-            'Suppression \(error hash=#([0-9A-F]+)#\):')
-        self._suppression_end = re.compile('^}\s*$')
+                r'Suppression \(error hash=#([0-9A-F]+)#\):')
+        self._suppression_end = re.compile(r'^}\s*$')
 
         # TODO b:169251326 terms below are set outside of this codebase
         # and should be updated when possible. ("master" -> "main")
-        self._main_name_re = re.compile('\[Running for master: "([^"]*)"')
+        self._main_name_re = re.compile(r'\[Running for master: "([^"]*)"')
         self.main_name = ''
 
         self._error_logging_start_re = re.compile('=' * 70)