Identify Chrome extension processes

Chrome extension processes are renderer processes, but it is useful to
break them out into their own category, to better see the impact that
they have on Chrome. A typical report from IdentifyChromeProcesses.py
now looks like this:

Chrome PIDs by process type:
c:\bin\chrome.exe (4976)
    browser     : 4976
    crashpad-handler : 8568
    extension   : 464 2964 3068 4808 6720 7004 8108 9084
    gpu-process : 6184
    renderer    : 2676 5624
    watcher     : 8840

bin/IdentifyChromeProcesses.py

@@ -67,6 +67,8 @@ def main():
         match = processTypeRe.match(commandLine)
         if match:
           type = match.groups()[0]
+          if commandLine.count(" --extension-process ") > 0:
+            type = "extension"
           browserPid = parentPid
         else:
           type = "browser"