Fix and reenable useless-object-inheritance.

Initial change generated using:
git ls-tree -r HEAD | awk '$1 != "120000" {print $NF}' | \
  grep '\.py$' | grep -v -e ^third_party/ -e '_pb2\.py' | \
  xargs sed -i 's/(object)//g'

Required only a handful of manual edits after that, mostly for
unrelated lint fixes.

BUG=None
TEST=run_tests, CQ

Change-Id: I0c57fdcf20124530ecd33ae3118506a2be9fc0ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4637436
Auto-Submit: Alex Klein <saklein@chromium.org>
Commit-Queue: Jack Rosenthal <jrosenth@chromium.org>
Tested-by: Alex Klein <saklein@chromium.org>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
diff --git a/scripts/sysmon/proc_metrics.py b/scripts/sysmon/proc_metrics.py
index 33be4e3..8222362 100644
--- a/scripts/sysmon/proc_metrics.py
+++ b/scripts/sysmon/proc_metrics.py
@@ -58,7 +58,7 @@
     collector.collect()
 
 
-class _ProcessMetricsCollector(object):
+class _ProcessMetricsCollector:
     """Class for collecting process metrics."""
 
     # We need to store some per process metrics of last run in order to
@@ -193,7 +193,7 @@
         self._other_metric.flush()
 
 
-class _ProcessMetric(object):
+class _ProcessMetric:
     """Class for gathering process metrics."""
 
     def __init__(self, process_name, test_func=lambda proc: True):
@@ -276,7 +276,7 @@
         self._io_counters = _IOCounters()
 
 
-class _CPUTimes(object):
+class _CPUTimes:
     """A container for CPU times metrics."""
 
     def __init__(self, v=None):
@@ -430,7 +430,7 @@
     return proc.name() == cmd and len(cmdline) > 1 and cmdline[1] == subcmd
 
 
-class _CPUTimes(object):
+class _CPUTimes:
     """A container for CPU times metrics."""
 
     def __init__(self, v=None):
@@ -473,7 +473,7 @@
         }
 
 
-class _IOCounters(object):
+class _IOCounters:
     """A container for I/O counter metrics."""
 
     def __init__(self, v=None):