Sampling profiling thread should be joined in a FILE thread

content/browser/tracing/tracing_controller_impl.h

Index: content/browser/tracing/tracing_controller_impl.h
diff --git a/content/browser/tracing/tracing_controller_impl.h b/content/browser/tracing/tracing_controller_impl.h
index ed3c8fd65193d00b65f7f4512446f3fd09c52069..81def13a1bc8a2d5b413ec943c6edc9427707933 100644
--- a/content/browser/tracing/tracing_controller_impl.h
+++ b/content/browser/tracing/tracing_controller_impl.h
@@ -117,6 +117,20 @@ class TracingControllerImpl : public TracingController {
 
   void OnWatchEventMatched();
 
+  void SetEnabled(const std::string& category_filter,
+                  int options,
+                  const base::Closure& callback);
+  void SetDisabled(const base::Closure& callback);
+  void OnEnableRecordingDone(const std::string& category_filter,
+                             int trace_options,
+                             const EnableRecordingDoneCallback& callback);
+  void OnDisableRecordingDone(const base::FilePath& result_file_path,
+                              const TracingFileResultCallback& callback);
+  void OnEnableMonitoringDone(const std::string& category_filter,
+                              int trace_options,
+                              const EnableMonitoringDoneCallback& callback);
+  void OnDisableMonitoringDone(const DisableMonitoringDoneCallback& callback);
+
   TraceMessageFilterMap trace_message_filters_;
   // Pending acks for DisableRecording.
   int pending_disable_recording_ack_count_;