[WIP]Create a V8 sampler library and tracing controller.

src/log.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_LOG_H_
 #define V8_LOG_H_
 
 #include <string>
 
 #include "src/allocation.h"
 #include "src/base/platform/elapsed-timer.h"
 #include "src/base/platform/platform.h"
 #include "src/objects.h"
 
 namespace v8 {
 
+class V8Sampler;
+
 namespace base {
 class Semaphore;
 }
 
 namespace internal {
 
 // Logger is used for collecting logging information from V8 during
 // execution. The result is dumped to a file.
 //
 // Available command line flags:
@@ skipping 112 matching lines @@
   V(NATIVE_FUNCTION_TAG,            "Function")                         \
   V(NATIVE_LAZY_COMPILE_TAG,        "LazyCompile")                      \
   V(NATIVE_SCRIPT_TAG,              "Script")
 // Note that 'NATIVE_' cases for functions and scripts are mapped onto
 // original tags when writing to the log.
 
 
 class JitLogger;
 class PerfBasicLogger;
 class LowLevelLogger;
-class Sampler;
+// class Sampler;
 
 class Logger {
  public:
   enum StartEnd { START = 0, END = 1 };
 
 #define DECLARE_ENUM(enum_item, ignore) enum_item,
   enum LogEventsAndTags {
     LOG_EVENTS_AND_TAGS_LIST(DECLARE_ENUM)
     NUMBER_OF_LOG_EVENTS
   };
 #undef DECLARE_ENUM
 
   // Acquires resources for logging if the right flags are set.
   bool SetUp(Isolate* isolate);
 
   // Sets the current code event handler.
   void SetCodeEventHandler(uint32_t options,
                            JitCodeEventHandler event_handler);
 
-  Sampler* sampler();
+  //Sampler* sampler();
+  V8Sampler* sampler();
 
   // Frees resources acquired in SetUp.
   // When a temporary file is used for the log, returns its stream descriptor,
   // leaving the file open.
   FILE* TearDown();
 
   // Emits an event with a string value -> (name, value).
   void StringEvent(const char* name, const char* value);
 
   // Emits an event with an int value -> (name, value).
@@ skipping 346 matching lines @@
 
   NameBuffer* name_buffer_;
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 
 #endif  // V8_LOG_H_