add ETW for V8 symbols

src/log.h

Index: src/log.h
diff --git a/src/log.h b/src/log.h
index 03c7b3b6705fd3460d5b12f532e3508a3e0ee17b..8c4a8d86cfbd5cf91576257d2f45592114f5f5b8 100644
--- a/src/log.h
+++ b/src/log.h
@@ -77,6 +77,7 @@ class Semaphore;
 class SlidingStateWindow;
 class Ticker;
 
+
 #undef LOG
 #define LOG(isolate, Call)                          \
   do {                                              \
@@ -271,7 +272,7 @@ class Logger {
   void LogRuntime(Vector<const char> format, JSArray* args);
 
   bool is_logging() {
-    return logging_nesting_ > 0;
+    return logging_nesting_ > 0 || CodeAddressCallbackEnabled();
   }
 
   // Pause/Resume collection of profiling data.
@@ -371,6 +372,9 @@ class Logger {
   // Returns whether profiler's sampler is active.
   bool IsProfilerSamplerActive();
 
+  // Returns whether symbol callback is enabled.
+  bool CodeAddressCallbackEnabled();
+
   // The sampler used by the profiler and the sliding state window.
   Ticker* ticker_;
 
@@ -425,6 +429,32 @@ class Logger {
   Address prev_code_;
 
   friend class CpuProfiler;
+
+  friend class CodeAddressNotification;
+
+  int notified_reset_;
+};
+
+
+class CodeAddressNotification {
+public:
+    // called by host to set callbacks - null turns off callbacks
+    static void SetCodeAddressEventCallback(CodeAddressEvent cb,
+                                            bool enumExisting);
+
+    // called by v8 when a symbol map is created or changed
+    static void WriteSymbolMap(Logger* logger,
+                               CodeAddressOperation op,
+                               const void* addr1,
+                               int len,
+                               const char* symbol,
+                               Logger::LogEventsAndTags tag,
+                               const void* addr2,
+                               int line);
+
+    // called by v8 to determine if callbacks are enabled
+    static bool IsEnabled();
+
 };