Add new timing mechanism to ftrace.

systrace/systrace/run_systrace.py

Index: systrace/systrace/run_systrace.py
diff --git a/systrace/systrace/run_systrace.py b/systrace/systrace/run_systrace.py
index 4b1f27c60539cbe902d4c206f6caad8219b1a7e9..32732fcc3c8ffe695133607d389b8e814817154b 100755
--- a/systrace/systrace/run_systrace.py
+++ b/systrace/systrace/run_systrace.py
@@ -24,6 +24,7 @@ if version != (2, 7):
 import imp
 import optparse
 import os
+import time
 
 _CATAPULT_DIR = os.path.join(
     os.path.dirname(os.path.abspath(__file__)), os.path.pardir, os.path.pardir)
@@ -242,6 +243,13 @@ def main():
   for a in agents:
     a.StartAgentTracing(options, categories, 10)
 
+  if options.trace_time:
+    print 'Tracing running for %d seconds.' % options.trace_time
+    time.sleep(options.trace_time)
+  else:
+    print 'Tracing running, stop with ENTER.'
+    raw_input()
+
   for a in agents:
     a.StopAgentTracing(10)