Implement system tracing for cros

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 c87dc836c689ec2a23014fc6f145a2ac6bbd2a22..5b671a6a277aa7db416284d58eaf41da4893141d 100644
--- a/content/browser/tracing/tracing_controller_impl.h
+++ b/content/browser/tracing/tracing_controller_impl.h
@@ -115,6 +115,9 @@ class TracingControllerImpl : public TracingController {
       const std::vector<std::string>& known_category_groups);
   void OnResultFileClosed();
 
+  void OnEndSystemTracingAcked(
+      const scoped_refptr<base::RefCountedString>& events_str_ptr);
+
   void OnCaptureMonitoringSnapshotAcked(
       TraceMessageFilter* trace_message_filter);
   void OnMonitoringSnapshotFileClosed();
@@ -157,6 +160,7 @@ class TracingControllerImpl : public TracingController {
 
   bool is_recording_;
   bool is_monitoring_;
+  bool is_system_tracing_;
   TracingController::Options options_;
 
   GetCategoriesDoneCallback pending_get_categories_done_callback_;