Revert "Switch profiler from isolates to threads"

runtime/vm/thread_interrupter.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_THREAD_INTERRUPTER_H_
 #define VM_THREAD_INTERRUPTER_H_
 
 #include "vm/allocation.h"
 #include "vm/signal_handler.h"
 #include "vm/os_thread.h"
 #include "vm/thread.h"
 
 namespace dart {
 
 class ThreadInterrupter : public AllStatic {
  public:
   static void InitOnce();
 
   static void Startup();
   static void Shutdown();
 
   // Delay between interrupts.
   static void SetInterruptPeriod(intptr_t period);
 
   // 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);
 
  private:
   static const intptr_t kMaxThreads = 4096;
   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_;
   static intptr_t current_wait_time_;
 
   static bool InDeepSleep() {
     return current_wait_time_ == Monitor::kNoTimeout;
   }
 
   static void UpdateStateObject(ThreadInterruptCallback callback, void* data);
 
   static void ThreadMain(uword parameters);
 
   static void InstallSignalHandler();
 
   static void RemoveSignalHandler();
 
   friend class ThreadInterrupterVisitIsolates;
 };
 
+void ThreadInterruptNoOp(const InterruptedThreadState& state, void* data);
+
 }  // namespace dart
 
 #endif  // VM_THREAD_INTERRUPTER_H_