Update buildbots to parse new telemetry JSON format.

scripts/slave/process_log_utils.py

Index: scripts/slave/process_log_utils.py
diff --git a/scripts/slave/process_log_utils.py b/scripts/slave/process_log_utils.py
index 241cedeec2a6aa5369aeb205ab345159ef442a11..c383b4acbfe17e429d0ed605e743fe7ebcc56676 100644
--- a/scripts/slave/process_log_utils.py
+++ b/scripts/slave/process_log_utils.py
@@ -166,6 +166,10 @@ class PerformanceLogProcessor(object):
 
     self._percentiles = [.1, .25, .5, .75, .90, .95, .99]
 
+  def IsChartJson(self):
+    """This is not the new telemetry --chartjson output format."""
+    return False
+
   def PerformanceLogs(self):
     if not self._finalized:
       self._FinalizeProcessing()