Add script to summarize CPU usage by command line

This adds a .wpaProfile file and python script to scan a trace and
summarize CPU usage by command line. The profile contains tables for
mapping from process to command line and process to CPU usage. The
script assumes that wpaexporter has been run and it processes the
resultant .csv files. The result is an output of CPU time and
command line pairs, sorted by CPU time consumed.

bin/CPUByCommandLine.py

@@ -0,0 +1,69 @@
+# Copyright 2019 Google Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+'''
+This script is designed to get CPU-time by process command line. It is used
+after running:
+wpaexporter -i trace.etl -profile CPUUsageByCommandLine.wpaProfile
+
+Running this wpaexporter command creates two .csv files, one mapping from
+process to command line and another mapping from process to CPU usage.
+Due to PID reuse the results are not guaranteed but will be mostly accurate.
+This was initially written in order to analyze CPU usage by Python scripts in
+Chromium's build.
+'''
+
+from __future__ import print_function
+
+import re
+import sys
+
+commandlines = open("Processes_ProcessCommandLines.csv").readlines()
+cpuusages = open("CPU_Usage_(Precise)_Randomascii_CPU_Summary_by_Process.csv").readlines()
+
+commandLinesByProcess = {}
+for line in commandlines[1:]:
+  # Typical lines look like this:
+  # conhost.exe (22628),\??\C:\WINDOWS\system32\conhost.exe 0x4
+  process, commandline = re.match(r'(.* \(\d+\)),(.*)\n', line).groups()
+  commandLinesByProcess[process] = commandline
+
+cpuusageByProcess = {}
+for line in cpuusages[1:]:
+  # Typical lines look like this:
+  # Idle (0),23871651,"20,726,984.943082"
+  # Quotes will be present when the numbers contain embedded commas.
+  match = re.match(r'(.*),\d+,"?([\d,.]*)"?\n', line)
+  process, cpuusage = match.groups()
+  # If a process ID is reused for a process of the same name then some data
+  # will be overwritten. Print a warning in that case.
+  if process in cpuusageByProcess:
+    print('Duplicate process/pid pair: %s' % process, file=sys.stderr)
+  cpuusageByProcess[process] = cpuusage
+
+cpuusageAndCommandline = []
+for process in commandLinesByProcess.keys():
+  # Some processes will not have run at all during the trace. That is fine.
+  if process in cpuusageByProcess:
+    # wpaexporter puts commas in some large numbers. This fixup code will
+    # presumably fail in some locales. Oh well.
+    cpuusage = float(cpuusageByProcess[process].replace(',', ''))
+    cpuusageAndCommandline += [[cpuusage, commandLinesByProcess[process]]]
+
+# Put the processes with the most CPU usage at the top.
+cpuusageAndCommandline.sort()
+cpuusageAndCommandline.reverse()
+
+for cpuusage, commandline in cpuusageAndCommandline:
+  print('%6.3f s - %s' % (cpuusage / 1000, commandline))