Replacing circular queue by single buffer in CPU Profiler.

src/platform-cygwin.cc

Index: src/platform-cygwin.cc
diff --git a/src/platform-cygwin.cc b/src/platform-cygwin.cc
index 7ef9f2469f84e13f2997a310ddbf79572a1dbee1..8835904273da49d68ee82467873bc85fcde70670 100644
--- a/src/platform-cygwin.cc
+++ b/src/platform-cygwin.cc
@@ -692,9 +692,8 @@ class SamplerThread : public Thread {
     CONTEXT context;
     memset(&context, 0, sizeof(context));
 
-    TickSample sample_obj;
-    TickSample* sample = CpuProfiler::TickSampleEvent(sampler->isolate());
-    if (sample == NULL) sample = &sample_obj;
+    TickSample* sample = CpuProfiler::StartTickSampleEvent(sampler->isolate());
+    if (sample == NULL) return;
 
     static const DWORD kSuspendFailed = static_cast<DWORD>(-1);
     if (SuspendThread(profiled_thread) == kSuspendFailed) return;
@@ -714,6 +713,7 @@ class SamplerThread : public Thread {
       sampler->SampleStack(sample);
       sampler->Tick(sample);
     }
+    CpuProfiler::FinishTickSampleEvent(sampler->isolate());
     ResumeThread(profiled_thread);
   }