Integrate Chrome tracing with V8 (WIP)

src/log.h

Index: src/log.h
diff --git a/src/log.h b/src/log.h
index abf35f0ebc5ddcf0373f598d0cf48eee1d479e5c..7619f15aeac4c571add8e8d4a81c466a6a254c06 100644
--- a/src/log.h
+++ b/src/log.h
@@ -152,6 +152,7 @@ class Sampler;
 class Logger {
  public:
   enum StartEnd { START = 0, END = 1 };
+  enum Overhead { LOW = 0, NORMAL = 1, HIGH = 2 };
 
 #define DECLARE_ENUM(enum_item, ignore) enum_item,
   enum LogEventsAndTags {
@@ -303,7 +304,7 @@ class Logger {
   static void DefaultEventLoggerSentinel(const char* name, int event) {}
 
   INLINE(static void CallEventLogger(Isolate* isolate, const char* name,
-                                     StartEnd se, bool expose_to_api));
+                                     StartEnd se, Overhead overhead));
 
   // ==== Events logged by --log-regexp ====
   // Regexp compilation and execution events.
@@ -422,19 +423,19 @@ class Logger {
 };
 
 
-#define TIMER_EVENTS_LIST(V)    \
-  V(RecompileSynchronous, true) \
-  V(RecompileConcurrent, true)  \
-  V(CompileFullCode, true)      \
-  V(Execute, true)              \
-  V(External, true)             \
-  V(IcMiss, false)
+#define TIMER_EVENTS_LIST(V)      \
+  V(RecompileSynchronous, NORMAL) \
+  V(RecompileConcurrent, NORMAL)  \
+  V(CompileFullCode, NORMAL)      \
+  V(Execute, NORMAL)              \
+  V(External, NORMAL)             \
+  V(IcMiss, HIGH)
 
-#define V(TimerName, expose)                                                  \
+#define V(TimerName, TimerOverhead)                                           \
   class TimerEvent##TimerName : public AllStatic {                            \
    public:                                                                    \
     static const char* name(void* unused = NULL) { return "V8." #TimerName; } \
-    static bool expose_to_api() { return expose; }                            \
+    static Logger::Overhead overhead() { return Logger::TimerOverhead; }      \
   };
 TIMER_EVENTS_LIST(V)
 #undef V