Create libsampler as V8 sampler library.

test/cctest/test-cpu-profiler.cc

Index: test/cctest/test-cpu-profiler.cc
diff --git a/test/cctest/test-cpu-profiler.cc b/test/cctest/test-cpu-profiler.cc
index e4eceeceab77641b7599424a249196346f5c461a..7740a1d9bf25572140bc33170e58e92472faced7 100644
--- a/test/cctest/test-cpu-profiler.cc
+++ b/test/cctest/test-cpu-profiler.cc
@@ -422,7 +422,7 @@ static v8::CpuProfile* RunProfiler(v8::Local<v8::Context> env,
   cpu_profiler->SetSamplingInterval(100);
   cpu_profiler->StartProfiling(profile_name, collect_samples);
 
-  i::Sampler* sampler =
+  v8::sampler::Sampler* sampler =
       reinterpret_cast<i::Isolate*>(env->GetIsolate())->logger()->sampler();
   sampler->StartCountingSamples();
   do {