telemetry: Make trace profiler work with trace-based benchmarks.

tools/perf/measurements/rasterize_and_record.py

Index: tools/perf/measurements/rasterize_and_record.py
diff --git a/tools/perf/measurements/rasterize_and_record.py b/tools/perf/measurements/rasterize_and_record.py
index 4ed5a0942e0808f28f9c0fc9cac36980f07bc3a7..424fdac11721e12f20a7084509915a1ebbb9946d 100644
--- a/tools/perf/measurements/rasterize_and_record.py
+++ b/tools/perf/measurements/rasterize_and_record.py
@@ -148,7 +148,7 @@ class RasterizeAndRecord(page_measurement.PageMeasurement):
         });
     """)
 
-    tab.browser.StartTracing('webkit,webkit.console,benchmark', 60)
+    tab.browser.StartTracing('webkit.console,benchmark', 60)
     self._metrics.Start()
 
     tab.ExecuteJavaScript("""
@@ -166,10 +166,9 @@ class RasterizeAndRecord(page_measurement.PageMeasurement):
     time.sleep(float(self.options.stop_wait_time))
     tab.ExecuteJavaScript('console.timeEnd("measureNextFrame")')
 
-    tab.browser.StopTracing()
+    timeline = tab.browser.StopTracing().AsTimelineModel()

[tonyg, 2013/09/12 00:49:55]

I suspect this line might be a little expensive which is why we bothered to
self._metrics.Stop() before AsTimelineModel().

Suggest flipping the order of this and the next line.

[ernstm, 2013/09/12 18:06:07]

Done.

     self._metrics.Stop()
 
-    timeline = tab.browser.GetTraceResultAndReset().AsTimelineModel()
     collector = StatsCollector(timeline)
     collector.GatherRenderingStats()