Move timeline and importers to use telemetry.value.TraceValue

tools/telemetry/telemetry/web_perf/timeline_based_measurement.py

Index: tools/telemetry/telemetry/web_perf/timeline_based_measurement.py
diff --git a/tools/telemetry/telemetry/web_perf/timeline_based_measurement.py b/tools/telemetry/telemetry/web_perf/timeline_based_measurement.py
index e6050955a85b337a01a070c1bd9143dd727768a3..26ab6814a212dd38763597708e74320a2cce2c78 100644
--- a/tools/telemetry/telemetry/web_perf/timeline_based_measurement.py
+++ b/tools/telemetry/telemetry/web_perf/timeline_based_measurement.py
@@ -169,20 +169,20 @@ class TimelineBasedMeasurement(page_measurement.PageMeasurement):
 
   def MeasurePage(self, page, tab, results):
     """ Collect all possible metrics and added them to results. """
-    trace_result = tab.browser.StopTracing()
+    trace_value = tab.browser.StopTracing()
     trace_dir = self.options.trace_dir
     if trace_dir:
       trace_file_path = util.GetSequentialFileName(
           os.path.join(trace_dir, 'trace')) + '.json'
       try:
         with open(trace_file_path, 'w') as f:
-          trace_result.Serialize(f)
+          trace_value.Serialize(f)
         results.AddValue(string_value_module.StringValue(
             page, 'trace_path', 'string', trace_file_path))
       except IOError, e:
         logging.error('Cannot open %s. %s' % (trace_file_path, e))
 
-    model = model_module.TimelineModel(trace_result)
+    model = model_module.TimelineModel(trace_value)
     renderer_thread = model.GetRendererThreadFromTabId(tab.id)
     meta_metrics = _TimelineBasedMetrics(
         model, renderer_thread, _GetMetricFromMetricType)