Use Systrace tracing controller in profile_chrome

systrace/profile_chrome/profiler_unittest.py

Index: systrace/profile_chrome/profiler_unittest.py
diff --git a/systrace/profile_chrome/profiler_unittest.py b/systrace/profile_chrome/profiler_unittest.py
index cffcf5ff3254ab76cf2924ed49342f5c3fdea655..9528db67ca10c273cbae48f752c80351f9ea1ba3 100644
--- a/systrace/profile_chrome/profiler_unittest.py
+++ b/systrace/profile_chrome/profiler_unittest.py
@@ -23,17 +23,19 @@ class FakeAgent(object):
   def StartAgentTracing(self, config, timeout=None):
     self.config = config
     self.timeout = timeout
+    return True
 
   # pylint: disable=unused-argument
   def StopAgentTracing(self, timeout=None):
     self.stopped = True
+    return True
 
   # pylint: disable=unused-argument
   def GetResults(self, timeout=None):
-    trace_data = open(self.PullTrace()).read()
+    trace_data = open(self._PullTrace()).read()
     return trace_result.TraceResult('fakeData', trace_data)
 
-  def PullTrace(self):
+  def _PullTrace(self):
     with tempfile.NamedTemporaryFile(delete=False) as f:
       self.filename = f.name
       f.write(self.contents)