LatencyInfo trace_id_ no longer dependent on sequence_number.

ui/latency/latency_info.h

 // Copyright 2013 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.
 
 #ifndef UI_LATENCY_LATENCY_INFO_H_
 #define UI_LATENCY_LATENCY_INFO_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 190 matching lines @@
 
   const LatencyMap& latency_components() const { return latency_components_; }
 
   const SourceEventType& source_event_type() const {
     return source_event_type_;
   }
   void set_source_event_type(SourceEventType type) {
     source_event_type_ = type;
   }
 
+  bool began() const { return began_; }
   bool terminated() const { return terminated_; }
   void set_coalesced() { coalesced_ = true; }
   bool coalesced() const { return coalesced_; }
   int64_t trace_id() const { return trace_id_; }
+  void set_trace_id(int64_t trace_id) { trace_id_ = trace_id; }
 
  private:
   void AddLatencyNumberWithTimestampImpl(LatencyComponentType component,
                                          int64_t id,
                                          int64_t component_sequence_number,
                                          base::TimeTicks time,
                                          uint32_t event_count,
                                          const char* trace_name_str);
 
   // Converts latencyinfo into format that can be dumped into trace buffer.
   std::unique_ptr<base::trace_event::ConvertableToTraceFormat>
   AsTraceableData();
 
   // Shown as part of the name of the trace event for this LatencyInfo.
   // String is empty if no tracing is enabled.
   std::string trace_name_;
 
   LatencyMap latency_components_;
 
   // The unique id for matching the ASYNC_BEGIN/END trace event.
   int64_t trace_id_;
   // Whether this event has been coalesced into another event.
   bool coalesced_;
+  // Whether a begin component has been added.
+  bool began_;
   // Whether a terminal component has been added.
   bool terminated_;
   // Stores the type of the first source event.
   SourceEventType source_event_type_;
 
 #if !defined(OS_IOS)
   friend struct IPC::ParamTraits<ui::LatencyInfo>;
   friend struct mojo::StructTraits<ui::mojom::LatencyInfoDataView,
                                    ui::LatencyInfo>;
 #endif
 };
 
 // This is declared here for use in gtest-based unit tests, but is defined in
 // //ui/latency:test_support target.
 // Without this the default PrintTo template in gtest tries to pass LatencyInfo
 // by value, which leads to an alignment compile error on Windows.
 void PrintTo(const LatencyInfo& latency, ::std::ostream* os);
 
 }  // namespace ui
 
 #endif  // UI_LATENCY_LATENCY_INFO_H_