Fix call stack sampling for the case when native callback invokes JS function

src/sampler.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 51 matching lines @@
 
 #include "v8.h"
 
 #include "cpu-profiler.h"
 #include "flags.h"
 #include "frames-inl.h"
 #include "log.h"
 #include "platform.h"
 #include "simulator.h"
 #include "v8threads.h"
+#include "vm-state-inl.h"
 
 
 #if defined(__ANDROID__) && !defined(__BIONIC_HAVE_UCONTEXT_T)
 
 // Not all versions of Android's C library provide ucontext_t.
 // Detect this and provide custom but compatible definitions. Note that these
 // follow the GLibc naming convention to access register values from
 // mcontext_t.
 //
 // See http://code.google.com/p/android/issues/detail?id=34784
@@ skipping 532 matching lines @@
   // Avoid collecting traces while doing GC.
   if (state == GC) return;
 
   const Address js_entry_sp =
       Isolate::js_entry_sp(isolate->thread_local_top());
   if (js_entry_sp == 0) {
     // Not executing JS now.
     return;
   }
 
-  const Address callback = isolate->external_callback();
-  if (callback != NULL) {
-    external_callback = callback;
+  ExternalCallbackScope* scope = isolate->external_callback_scope();
+  Address handler = Isolate::handler(isolate->thread_local_top());
+  // If there is a handler on top of the external callback scope then
+  // we have already entrered JavaScript again and the external callback
+  // is not the top function.
+  if (scope && scope->scope_address() < handler) {
+    external_callback = scope->callback();
     has_external_callback = true;
   } else {
     // Sample potential return address value for frameless invocation of
     // stubs (we'll figure out later, if this value makes sense).
     tos = Memory::Address_at(regs.sp);
     has_external_callback = false;
   }
 
   SafeStackFrameIterator it(isolate, regs.fp, regs.sp, js_entry_sp);
   top_frame_type = it.top_frame_type();
@@ skipping 54 matching lines @@
   sample->Init(isolate_, state);
   if (is_counting_samples_) {
     if (sample->state == JS || sample->state == EXTERNAL) {
       ++js_and_external_sample_count_;
     }
   }
   Tick(sample);
 }
 
 } }  // namespace v8::internal