Add support for allowing an embedder to get the V8 profile timer event logs.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 897197bc75eb240474bbb6c110bb625245fda0be..b35ca716991c7c8de53dee9eb0a66735d0f2e3fb 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -340,6 +340,7 @@ typedef List<HeapObject*> DebugObjectCache;
   /* A previously allocated buffer of kMinimalBufferSize bytes, or NULL. */    \
   V(byte*, assembler_spare_buffer, NULL)                                       \
   V(FatalErrorCallback, exception_behavior, NULL)                              \
+  V(LogEventCallback, event_logger, NULL)                                      \
   V(AllowCodeGenerationFromStringsCallback, allow_code_gen_callback, NULL)     \
   /* To distinguish the function templates, so that we can find them in the */ \
   /* function cache of the native context. */                                  \