[Telemetry] Change trace_data to hold a list of raw trace data for each trace part

telemetry/telemetry/timeline/model_unittest.py

Index: telemetry/telemetry/timeline/model_unittest.py
diff --git a/telemetry/telemetry/timeline/model_unittest.py b/telemetry/telemetry/timeline/model_unittest.py
index d8d6a575e273753ff10e8ed061e01034fbb9d487..4520f271d24cd47ce077906ff09b717be7979422 100644
--- a/telemetry/telemetry/timeline/model_unittest.py
+++ b/telemetry/telemetry/timeline/model_unittest.py
@@ -14,11 +14,11 @@ class TimelineModelUnittest(unittest.TestCase):
 
   def testBrowserProcess(self):
     builder = trace_data.TraceDataBuilder()
-    builder.AddEventsTo(trace_data.CHROME_TRACE_PART, [
-      {"name": "process_name", "args": {"name": "Browser"},
-       "pid": 5, "ph": "M"},
-      {"name": "thread_name", "args": {"name": "CrBrowserMain"},
-       "pid": 5, "tid": 32578, "ph": "M"}
-    ])
+    builder.AddTraceFor(trace_data.CHROME_TRACE_PART, {
+      "traceEvents": [
+        {"name": "process_name", "args": {"name": "Browser"},
+         "pid": 5, "ph": "M"},
+        {"name": "thread_name", "args": {"name": "CrBrowserMain"},
+         "pid": 5, "tid": 32578, "ph": "M"}]})
     model = model_module.TimelineModel(builder.AsData())
     self.assertEquals(5, model.browser_process.pid)