Fix CPU profiler crash in start / stop sequence when non-existent name is passed

src/cpu-profiler.cc

 // Copyright 2010 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 458 matching lines @@
       Logger::LogAccessorCallbacks();
     }
     // Enable stack sampling.
     reinterpret_cast<Sampler*>(Logger::ticker_)->Start();
   }
 }
 
 
 CpuProfile* CpuProfiler::StopCollectingProfile(const char* title) {
   const double actual_sampling_rate = generator_->actual_sampling_rate();
-  StopProcessorIfLastProfile();
+  StopProcessorIfLastProfile(title);
   CpuProfile* result =
       profiles_->StopProfiling(TokenEnumerator::kNoSecurityToken,
                                title,
                                actual_sampling_rate);
   if (result != NULL) {
     result->Print();
   }
   return result;
 }
 
 
 CpuProfile* CpuProfiler::StopCollectingProfile(Object* security_token,
                                                String* title) {
   const double actual_sampling_rate = generator_->actual_sampling_rate();
-  StopProcessorIfLastProfile();
+  const char* profile_title = profiles_->GetName(title);
+  StopProcessorIfLastProfile(profile_title);
   int token = token_enumerator_->GetTokenId(security_token);
-  return profiles_->StopProfiling(token, title, actual_sampling_rate);
+  return profiles_->StopProfiling(token, profile_title, actual_sampling_rate);
 }
 
 
-void CpuProfiler::StopProcessorIfLastProfile() {
-  if (profiles_->is_last_profile()) {
+void CpuProfiler::StopProcessorIfLastProfile(const char* title) {
+  if (profiles_->IsLastProfile(title)) {
     reinterpret_cast<Sampler*>(Logger::ticker_)->Stop();
     processor_->Stop();
     processor_->Join();
     delete processor_;
     delete generator_;
     processor_ = NULL;
     generator_ = NULL;
     Logger::logging_nesting_ = saved_logging_nesting_;
   }
 }
@@ skipping 17 matching lines @@
 void CpuProfiler::TearDown() {
 #ifdef ENABLE_LOGGING_AND_PROFILING
   if (singleton_ != NULL) {
     delete singleton_;
   }
   singleton_ = NULL;
 #endif
 }
 
 } }  // namespace v8::internal