Switch profiler from isolates to threads [second landing]

runtime/vm/debugger.cc

Index: runtime/vm/debugger.cc
diff --git a/runtime/vm/debugger.cc b/runtime/vm/debugger.cc
index 0b3e26139a114c88b0c5c5638e52481a0dbdaf70..2c4d54bf04c0bd6dbd76796dab0c00c1fefdd77a 100644
--- a/runtime/vm/debugger.cc
+++ b/runtime/vm/debugger.cc
@@ -2515,7 +2515,12 @@ void Debugger::Pause(DebuggerEvent* event) {
   pause_event_->UpdateTimestamp();
   obj_cache_ = new RemoteObjectCache(64);
 
-  InvokeEventHandler(event);
+  // We are about to invoke the debuggers event handler. Disable interrupts
+  // for this thread while waiting for debug commands over the service protocol.
+  {
+    DisableThreadInterruptsScope dtis(Thread::Current());
+    InvokeEventHandler(event);
+  }
 
   pause_event_ = NULL;
   obj_cache_ = NULL;    // Zone allocated
@@ -2556,11 +2561,6 @@ void Debugger::HandleSteppingRequest(DebuggerStackTrace* stack_trace) {
       }
     }
   }
-  if (!isolate_->single_step()) {
-    // We are no longer single stepping, make sure that the ThreadInterrupter
-    // is awake.
-    ThreadInterrupter::WakeUp();
-  }
 }