[Telemetry][Tracing] Split StopTracing and CollectTraceData for Chrome Tracing Agent.

telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import logging
 import re
 import socket
 import sys
 
 from telemetry.core import exceptions
@@ skipping 86 matching lines @@
     self._devtools_port = devtools_port
     self._remote_devtools_port = remote_devtools_port
     self._devtools_http = devtools_http.DevToolsHttp(devtools_port)
     self._browser_inspector_websocket = None
     self._tracing_backend = None
     self._memory_backend = None
     self._app_backend = app_backend
     self._devtools_context_map_backend = _DevToolsContextMapBackend(
         self._app_backend, self)
 
+    self._tab_ids = None

[Zhen Wang, 2016/07/21 19:45:19]

Does this tab id thing come from rebase?

[rnephew (Reviews Here), 2016/07/21 19:55:20]

No, it was required to fix a failing test this CL introduced. This is populated
in StopChromeTracing (javascript needs to be evaluated before stopping chrome
tracing) and used in CollectChromeTracingData to add things to the
trace_data_builder (cant be done in StopChromeTracing since it no longer gets
passed the trace_data_builder.)

+
     if not self.supports_tracing:
       return
     chrome_tracing_devtools_manager.RegisterDevToolsClient(
         self, self._app_backend.platform_backend)
 
     # Telemetry has started Chrome tracing if there is trace config, so start
     # tracing on this newly created devtools client if needed.
     trace_config = (self._app_backend.platform_backend
                     .tracing_controller_backend.GetChromeTraceConfig())
     if not trace_config:
@@ skipping 215 matching lines @@
     """
     assert trace_config and trace_config.enable_chrome_trace
     self._CreateTracingBackendIfNeeded()
     return self._tracing_backend.StartTracing(
         trace_config.chrome_trace_config, timeout)
 
   def RecordChromeClockSyncMarker(self, sync_id):
     assert self.is_tracing_running, 'Tracing must be running to clock sync.'
     self._tracing_backend.RecordClockSyncMarker(sync_id)
 
-  def StopChromeTracing(self, trace_data_builder, timeout=30):
+  def StopChromeTracing(self):
     assert self.is_tracing_running
+    self._tab_ids = []
     try:
       context_map = self.GetUpdatedInspectableContexts()
       for context in context_map.contexts:
         if context['type'] not in ['iframe', 'page', 'webview']:
           continue
         context_id = context['id']
         backend = context_map.GetInspectorBackend(context_id)
         backend.EvaluateJavaScript(
             "console.time('" + backend.id + "');" +
             "console.timeEnd('" + backend.id + "');" +
             "console.time.toString().indexOf('[native code]') != -1;")
+        self._tab_ids.append(backend.id)
+    finally:
+      self._tracing_backend.StopTracing()
+
+  def CollectChromeTracingData(self, trace_data_builder, timeout=30):
+    try:
+      for tab_id in self._tab_ids:
         trace_data_builder.AddEventsTo(
-            trace_data_module.TAB_ID_PART, [backend.id])
+            trace_data_module.TAB_ID_PART, [tab_id])
+      self._tab_ids = None
     finally:
-      self._tracing_backend.StopTracing(trace_data_builder, timeout)
+      self._tracing_backend.CollectTraceData(trace_data_builder, timeout)
 
   def DumpMemory(self, timeout=30):
     """Dumps memory.
 
     Returns:
       GUID of the generated dump if successful, None otherwise.
 
     Raises:
       TracingTimeoutException: If more than |timeout| seconds has passed
       since the last time any data is received.
@@ skipping 101 matching lines @@
                         % context_id)
           continue
       valid_contexts.append(context)
     self._contexts = valid_contexts
 
   def Clear(self):
     for backend in self._inspector_backends_dict.values():
       backend.Disconnect()
     self._inspector_backends_dict = {}
     self._contexts = None