Ensure Sample instance_size is always set.

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/utils.h"
 
 #include "vm/allocation.h"
 #include "vm/atomic.h"
 #include "vm/code_patcher.h"
 #include "vm/isolate.h"
@@ skipping 22 matching lines @@
 DEFINE_FLAG(int, profile_depth, 8,
             "Maximum number stack frames walked. Minimum 1. Maximum 128.");
 
 bool Profiler::initialized_ = false;
 SampleBuffer* Profiler::sample_buffer_ = NULL;
 
 void Profiler::InitOnce() {
   const int kMinimumProfilePeriod = 250;
   const int kMinimumDepth = 1;
   const int kMaximumDepth = 128;
-  if (!FLAG_profile) {
-    return;
-  }
-  ASSERT(!initialized_);
   // Place some sane restrictions on user controlled flags.
   if (FLAG_profile_period < kMinimumProfilePeriod) {
     FLAG_profile_period = kMinimumProfilePeriod;
   }
   if (FLAG_profile_depth < kMinimumDepth) {
     FLAG_profile_depth = kMinimumDepth;
   } else if (FLAG_profile_depth > kMaximumDepth) {
     FLAG_profile_depth = kMaximumDepth;
   }
   Sample::InitOnce();
+  if (!FLAG_profile) {
+    return;
+  }
+  ASSERT(!initialized_);
   sample_buffer_ = new SampleBuffer();
   NativeSymbolResolver::InitOnce();
   ThreadInterrupter::InitOnce();
   ThreadInterrupter::SetInterruptPeriod(FLAG_profile_period);
   initialized_ = true;
 }
 
 
 void Profiler::Shutdown() {
   if (!FLAG_profile) {
@@ skipping 762 matching lines @@
     return false;
   }
   uintptr_t cursor = reinterpret_cast<uintptr_t>(fp);
   cursor += sizeof(fp);
   bool r = cursor >= lower_bound_ && cursor < stack_upper_;
   return r;
 }
 
 
 }  // namespace dart