Revert of Create libsampler as V8 sampler library.

src/log.h

Index: src/log.h
diff --git a/src/log.h b/src/log.h
index dec389a3a9aef26b9b4db8e33bfb3bee3964b32c..9953b4cd8735468e157c2b18b008a541afece107 100644
--- a/src/log.h
+++ b/src/log.h
@@ -17,10 +17,6 @@
 
 namespace base {
 class Semaphore;
-}
-
-namespace sampler {
-class Sampler;
 }
 
 namespace internal {
@@ -145,6 +141,7 @@
 class PerfBasicLogger;
 class LowLevelLogger;
 class PerfJitLogger;
+class Sampler;
 
 class Logger {
  public:
@@ -164,7 +161,7 @@
   void SetCodeEventHandler(uint32_t options,
                            JitCodeEventHandler event_handler);
 
-  sampler::Sampler* sampler();
+  Sampler* sampler();
 
   // Frees resources acquired in SetUp.
   // When a temporary file is used for the log, returns its stream descriptor,