When deciding not to walk the native stack, don't overwrite the vm_tag set in SetupSample.

runtime/vm/profiler.cc

 // 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.
 
 #include "platform/address_sanitizer.h"
 #include "platform/memory_sanitizer.h"
 #include "platform/utils.h"
 
 #include "vm/allocation.h"
 #include "vm/atomic.h"
@@ skipping 694 matching lines @@
   if (FLAG_profile_vm) {
     // Always walk the native stack collecting both native and Dart frames.
     native_stack_walker->walk();
   } else if (StubCode::HasBeenInitialized() && exited_dart_code) {
     // We have a valid exit frame info, use the Dart stack walker.
     dart_exit_stack_walker->walk();
   } else if (StubCode::HasBeenInitialized() && in_dart_code) {
     // We are executing Dart code. We have frame pointers.
     dart_stack_walker->walk();
   } else {
-    sample->set_vm_tag(VMTag::kEmbedderTagId);
     sample->SetAt(0, pc);
   }
 
 #if defined(TARGET_OS_WINDOWS)
   // Use structured exception handling to trap guard page access.
   } __except(GuardPageExceptionFilter(GetExceptionInformation())) {
     // Sample collection triggered a guard page fault:
     // 1) discard entire sample.
     sample->set_ignore_sample(true);
 
@@ skipping 190 matching lines @@
     ProfilerDartExitStackWalker dart_exit_stack_walker(thread,
                                                        isolate,
                                                        sample,
                                                        sample_buffer);
     dart_exit_stack_walker.walk();
   } else {
     // Fall back.
     uintptr_t pc = GetProgramCounter();
     Sample* sample = SetupSample(thread, sample_buffer, os_thread->id());
     sample->SetAllocationCid(cid);
-    sample->set_vm_tag(VMTag::kEmbedderTagId);
     sample->SetAt(0, pc);
   }
 }
 
 
 void Profiler::SampleThread(Thread* thread,
                             const InterruptedThreadState& state) {
   ASSERT(thread != NULL);
   OSThread* os_thread = thread->os_thread();
   ASSERT(os_thread != NULL);
@@ skipping 426 matching lines @@
   }
 }
 
 
 ProcessedSampleBuffer::ProcessedSampleBuffer()
     : code_lookup_table_(new CodeLookupTable(Thread::Current())) {
   ASSERT(code_lookup_table_ != NULL);
 }
 
 }  // namespace dart