Revert "Switch profiler from isolates to threads"

runtime/vm/thread_interrupter.h

Index: runtime/vm/thread_interrupter.h
diff --git a/runtime/vm/thread_interrupter.h b/runtime/vm/thread_interrupter.h
index 9a70e497c413c221977b441884a0236e600f975c..9d3ccabd822df55de18c01e7541a6b1584f744bd 100644
--- a/runtime/vm/thread_interrupter.h
+++ b/runtime/vm/thread_interrupter.h
@@ -25,6 +25,13 @@ class ThreadInterrupter : public AllStatic {
   // Wake up the thread interrupter thread.
   static void WakeUp();
 
+  // Register the currently running thread for interrupts. If the current thread
+  // is already registered, callback and data will be updated.
+  static void Register(ThreadInterruptCallback callback, void* data);
+
+  // Unregister the currently running thread for interrupts.
+  static void Unregister();
+
   // Interrupt a thread.
   static void InterruptThread(Thread* thread);
 
@@ -33,7 +40,6 @@ class ThreadInterrupter : public AllStatic {
   static bool initialized_;
   static bool shutdown_;
   static bool thread_running_;
-  static bool woken_up_;
   static ThreadJoinId interrupter_thread_id_;
   static Monitor* monitor_;
   static intptr_t interrupt_period_;
@@ -54,6 +60,8 @@ class ThreadInterrupter : public AllStatic {
   friend class ThreadInterrupterVisitIsolates;
 };
 
+void ThreadInterruptNoOp(const InterruptedThreadState& state, void* data);
+
 }  // namespace dart
 
 #endif  // VM_THREAD_INTERRUPTER_H_