Refactor CpuProfiler.

src/log.h

Index: src/log.h
diff --git a/src/log.h b/src/log.h
index 91331f04fc068c0ad3b16149a70bc85971896a14..303e352898a0cd76a8774be863fbe787e3b56d65 100644
--- a/src/log.h
+++ b/src/log.h
@@ -89,6 +89,7 @@ class JitLogger;
 class PerfBasicLogger;
 class LowLevelLogger;
 class PerfJitLogger;
+class ProfilerListener;
 
 class Logger : public CodeEventListener {
  public:
@@ -101,8 +102,16 @@ class Logger : public CodeEventListener {
   void SetCodeEventHandler(uint32_t options,
                            JitCodeEventHandler event_handler);
 
+  // Sets up ProfilerListener.
+  void SetUpProfilerListener();
+
+  // Tear down ProfilerListener if it has no observers.
+  void TearDownProfilerListener();
+
   sampler::Sampler* sampler();
 
+  ProfilerListener* profiler_listener() { return profiler_listener_.get(); }
+
   // Frees resources acquired in SetUp.
   // When a temporary file is used for the log, returns its stream descriptor,
   // leaving the file open.
@@ -332,6 +341,7 @@ class Logger : public CodeEventListener {
   PerfJitLogger* perf_jit_logger_;
   LowLevelLogger* ll_logger_;
   JitLogger* jit_logger_;
+  std::unique_ptr<ProfilerListener> profiler_listener_;
   List<CodeEventListener*> listeners_;
 
   // Guards against multiple calls to TearDown() that can happen in some tests.