Adding flow traces for blink scheduler events

Source/platform/scheduler/Scheduler.h

Index: Source/platform/scheduler/Scheduler.h
diff --git a/Source/platform/scheduler/Scheduler.h b/Source/platform/scheduler/Scheduler.h
index 654764e53723ef12efb4cb601b124f88e5c426d2..be8ad4d66106eba6a7ccf64de00442ec4650176a 100644
--- a/Source/platform/scheduler/Scheduler.h
+++ b/Source/platform/scheduler/Scheduler.h
@@ -6,7 +6,7 @@
 #define Scheduler_h
 
 #include "platform/PlatformExport.h"
-#include "platform/TraceLocation.h"
+#include "platform/scheduler/TracedTask.h"
 #include "wtf/DoubleBufferedDeque.h"
 #include "wtf/Functional.h"
 #include "wtf/Noncopyable.h"
@@ -56,27 +56,16 @@ private:
     friend class MainThreadPendingTaskRunner;
     friend class MainThreadPendingHighPriorityTaskRunner;
 
-    class TracedTask {
-    public:
-        TracedTask(const Task& task, const TraceLocation& location)
-            : m_task(task)
-            , m_location(location) { }
-
-        void run();
-
-    private:
-        Task m_task;
-        TraceLocation m_location;
-    };
-
     Scheduler();
     ~Scheduler();
 
     void scheduleIdleTask(const TraceLocation&, const IdleTask&);
+    void postHighPriorityTaskInternal(const TraceLocation&, const Task&, const char* traceName);
 
     static void sharedTimerAdapter();
     void tickSharedTimer();
 
+
     bool hasPendingHighPriorityWork() const;
     bool swapQueuesAndRunPendingTasks();
     void swapQueuesRunPendingTasksAndAllowHighPriorityTaskRunnerPosting();
@@ -87,6 +76,8 @@ private:
     // Must be called while m_pendingTasksMutex is locked.
     void maybePostMainThreadPendingHighPriorityTaskRunner();
 
+    int generateFlowTraceID();
+
     static Scheduler* s_sharedScheduler;
 
     // Should only be accessed from the main thread.
@@ -99,7 +90,10 @@ private:
     Mutex m_pendingTasksMutex;
     DoubleBufferedDeque<TracedTask> m_pendingHighPriorityTasks;
 
+    // Declared volatile as they are atomically incremented.
     volatile int m_highPriorityTaskCount;
+    volatile int m_nextFlowTraceID;
+
     bool m_highPriorityTaskRunnerPosted;
 };