Update from https://crrev.com/327068

base/trace_event/trace_event_impl.h

 // Copyright (c) 2012 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 BASE_TRACE_EVENT_TRACE_EVENT_IMPL_H_
 #define BASE_TRACE_EVENT_TRACE_EVENT_IMPL_H_
 
 #include <stack>
 #include <string>
 #include <vector>
 
 #include "base/atomicops.h"
 #include "base/base_export.h"
 #include "base/callback.h"
 #include "base/containers/hash_tables.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_vector.h"
 #include "base/observer_list.h"
 #include "base/strings/string_util.h"
 #include "base/synchronization/condition_variable.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_local.h"
 
 // Older style trace macros with explicit id and extra data
 // Only these macros result in publishing data to ETW as currently implemented.
+// TODO(georgesak): Update/replace these with new ETW macros.
 #define TRACE_EVENT_BEGIN_ETW(name, id, extra) \
     base::trace_event::TraceLog::AddTraceEventEtw( \
         TRACE_EVENT_PHASE_BEGIN, \
         name, reinterpret_cast<const void*>(id), extra)
 
 #define TRACE_EVENT_END_ETW(name, id, extra) \
     base::trace_event::TraceLog::AddTraceEventEtw( \
         TRACE_EVENT_PHASE_END, \
         name, reinterpret_cast<const void*>(id), extra)
 
@@ skipping 400 matching lines @@
   // value with zero or more of the following bits. Used in this class only.
   // The TRACE_EVENT macros should only use the value as a bool.
   // These values must be in sync with macro values in TraceEvent.h in Blink.
   enum CategoryGroupEnabledFlags {
     // Category group enabled for the recording mode.
     ENABLED_FOR_RECORDING = 1 << 0,
     // Category group enabled for the monitoring mode.
     ENABLED_FOR_MONITORING = 1 << 1,
     // Category group enabled by SetEventCallbackEnabled().
     ENABLED_FOR_EVENT_CALLBACK = 1 << 2,
+    // Category group enabled to export events to ETW.
+    ENABLED_FOR_ETW_EXPORT = 1 << 3
   };
 
   static TraceLog* GetInstance();
 
   // Get set of known category groups. This can change as new code paths are
   // reached. The known category groups are inserted into |category_groups|.
   void GetKnownCategoryGroups(std::vector<std::string>* category_groups);
 
   // Retrieves a copy (for thread-safety) of the current CategoryFilter.
   CategoryFilter GetCurrentCategoryFilter();
@@ skipping 72 matching lines @@
   void SetEventCallbackDisabled();
 
   // Flush all collected events to the given output callback. The callback will
   // be called one or more times either synchronously or asynchronously from
   // the current thread with IPC-bite-size chunks. The string format is
   // undefined. Use TraceResultBuffer to convert one or more trace strings to
   // JSON. The callback can be null if the caller doesn't want any data.
   // Due to the implementation of thread-local buffers, flush can't be
   // done when tracing is enabled. If called when tracing is enabled, the
   // callback will be called directly with (empty_string, false) to indicate
-  // the end of this unsuccessful flush.
+  // the end of this unsuccessful flush. Flush does the serialization
+  // on the same thread if the caller doesn't set use_worker_thread explicitly.
   typedef base::Callback<void(const scoped_refptr<base::RefCountedString>&,
                               bool has_more_events)> OutputCallback;
-  void Flush(const OutputCallback& cb);
+  void Flush(const OutputCallback& cb, bool use_worker_thread = false);
   void FlushButLeaveBufferIntact(const OutputCallback& flush_output_callback);
 
   // Called by TRACE_EVENT* macros, don't call this directly.
   // The name parameter is a category group for example:
   // TRACE_EVENT0("renderer,webkit", "WebViewImpl::HandleInputEvent")
   static const unsigned char* GetCategoryGroupEnabled(const char* name);
   static const char* GetCategoryGroupName(
       const unsigned char* category_group_enabled);
 
   // Called by TRACE_EVENT* macros, don't call this directly.
@@ skipping 40 matching lines @@
   typedef base::Callback<void()> WatchEventCallback;
   void SetWatchEvent(const std::string& category_name,
                      const std::string& event_name,
                      const WatchEventCallback& callback);
   // Cancel the watch event. If tracing is enabled, this may race with the
   // watch event notification firing.
   void CancelWatchEvent();
 
   int process_id() const { return process_id_; }
 
+  uint64 MangleEventId(uint64 id);
+
   // Exposed for unittesting:
 
   void WaitSamplingEventForTesting();
 
   // Allows deleting our singleton instance.
   static void DeleteForTesting();
 
   // Allow tests to inspect TraceEvents.
   TraceEvent* GetEventByHandle(TraceEventHandle handle);
 
@@ skipping 88 matching lines @@
                                                      bool check_buffer_is_full);
   void CheckIfBufferIsFullWhileLocked();
   void SetDisabledWhileLocked();
 
   TraceEvent* GetEventByHandleInternal(TraceEventHandle handle,
                                        OptionalAutoLock* lock);
 
   // |generation| is used in the following callbacks to check if the callback
   // is called for the flush of the current |logged_events_|.
   void FlushCurrentThread(int generation);
-  void ConvertTraceEventsToTraceFormat(scoped_ptr<TraceBuffer> logged_events,
+  // Usually it runs on a different thread.
+  static void ConvertTraceEventsToTraceFormat(
+      scoped_ptr<TraceBuffer> logged_events,
       const TraceLog::OutputCallback& flush_output_callback);
   void FinishFlush(int generation);
   void OnFlushTimeout(int generation);
 
   int generation() const {
     return static_cast<int>(subtle::NoBarrier_Load(&generation_));
   }
   bool CheckGeneration(int generation) const {
     return generation == this->generation();
   }
@@ skipping 72 matching lines @@
 
   // For events which can't be added into the thread local buffer, e.g. events
   // from threads without a message loop.
   scoped_ptr<TraceBufferChunk> thread_shared_chunk_;
   size_t thread_shared_chunk_index_;
 
   // Set when asynchronous Flush is in progress.
   OutputCallback flush_output_callback_;
   scoped_refptr<MessageLoopProxy> flush_message_loop_proxy_;
   subtle::AtomicWord generation_;
+  bool use_worker_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceLog);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_IMPL_H_