Fix LogMan tracer to work correctly when process ids are reused.

tools/isolate/trace_inputs.py

Index: tools/isolate/trace_inputs.py
diff --git a/tools/isolate/trace_inputs.py b/tools/isolate/trace_inputs.py
index a24fde428b8b9dd30cc6fc1cac651140a36d1aaa..05c652be0b7e8b8517f1f0893b73cb37405b8493 100755
--- a/tools/isolate/trace_inputs.py
+++ b/tools/isolate/trace_inputs.py
@@ -2456,7 +2456,7 @@ class LogmanTrace(ApiBase):
 
     def handle_Process_End(self, line):
       pid = line[self.PID]
-      if pid in self._process_lookup:
+      if self._process_lookup.get(pid):
         logging.info('Terminated: %d' % pid)
         self._process_lookup[pid] = None
       else:
@@ -2491,7 +2491,7 @@ class LogmanTrace(ApiBase):
         proc = self.Process(self.blacklist, pid, None)
         self.root_process = proc
         ppid = None
-      elif ppid in self._process_lookup:
+      elif self._process_lookup.get(ppid):
         proc = self.Process(self.blacklist, pid, None)
         self._process_lookup[ppid].children.append(proc)
       else: