Revert "Switch profiler from isolates to threads"

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index 9f06cc73a1962ff065f02ef333356598898697eb..a02bbc7c0307ba912cdc9156c9c0b8357f390a99 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -550,12 +550,27 @@ class Isolate : public BaseIsolate {
     return defer_finalization_count_ == 0;
   }
 
+  Mutex* profiler_data_mutex() {
+    return &profiler_data_mutex_;
+  }
+
+  void set_profiler_data(IsolateProfilerData* profiler_data) {
+    profiler_data_ = profiler_data;
+  }
+
+  IsolateProfilerData* profiler_data() const {
+    return profiler_data_;
+  }
+
   void PrintJSON(JSONStream* stream, bool ref = true);
 
   CompilerStats* compiler_stats() {
     return compiler_stats_;
   }
 
+  // Returns the number of sampled threads.
+  intptr_t ProfileInterrupt();
+
   VMTagCounters* vm_tag_counters() {
     return &vm_tag_counters_;
   }
@@ -781,6 +796,9 @@ class Isolate : public BaseIsolate {
   // Trace buffer support.
   TraceBuffer* trace_buffer_;
 
+  IsolateProfilerData* profiler_data_;
+  Mutex profiler_data_mutex_;
+
   VMTagCounters vm_tag_counters_;
   RawGrowableObjectArray* tag_table_;