Perform CPU sampling by CPU sampling thread only iff processing thread is not running.

src/platform-cygwin.cc

Index: src/platform-cygwin.cc
diff --git a/src/platform-cygwin.cc b/src/platform-cygwin.cc
index e35df11a7c7bdfc8a8d754c570db22632b9b74e9..028aae327bbdd8a0dd390bad5d9f14977f55f1aa 100644
--- a/src/platform-cygwin.cc
+++ b/src/platform-cygwin.cc
@@ -698,8 +698,9 @@ class SamplerThread : public Thread {
     CONTEXT context;
     memset(&context, 0, sizeof(context));
 
+    TickSample sample_obj;
     TickSample* sample = CpuProfiler::StartTickSampleEvent(sampler->isolate());
-    if (sample == NULL) return;
+    if (sample == NULL) sample = &sample_obj;
 
     static const DWORD kSuspendFailed = static_cast<DWORD>(-1);
     if (SuspendThread(profiled_thread) == kSuspendFailed) return;
@@ -793,4 +794,12 @@ void Sampler::Stop() {
 }
 
 
+void Sampler::StartSampling() {
+}
+
+
+void Sampler::StopSampling() {
+}
+
+
 } }  // namespace v8::internal