Add logging of callbacks in prof-lazy mode.

src/log.h

Index: src/log.h
diff --git a/src/log.h b/src/log.h
index e7931ca42df8e49564685251aee195e566d76bdc..6570c74632dab75fb819c64b5e56d761188ad2c3 100644
--- a/src/log.h
+++ b/src/log.h
@@ -122,6 +122,7 @@ class VMState BASE_EMBEDDED {
   V(CALL_MISS_TAG,                  "CallMiss",               "cm")       \
   V(CALL_NORMAL_TAG,                "CallNormal",             "cn")       \
   V(CALL_PRE_MONOMORPHIC_TAG,       "CallPreMonomorphic",     "cpm")      \
+  V(CALLBACK_TAG,                   "Callback",               "cb")       \
   V(EVAL_TAG,                       "Eval",                   "e")        \
   V(FUNCTION_TAG,                   "Function",               "f")        \
   V(KEYED_LOAD_IC_TAG,              "KeyedLoadIC",            "klic")     \
@@ -200,6 +201,9 @@ class Logger {
 
 
   // ==== Events logged by --log-code. ====
+  // Emits a code event for a callback function.
+  static void CallbackEvent(const char* class_name, const char* method_name,
+                            Address entry_point);
   // Emits a code create event.
   static void CodeCreateEvent(LogEventsAndTags tag,
                               Code* code, const char* source);
@@ -267,6 +271,10 @@ class Logger {
   static void LogCompiledFunctions();
   // Used for logging stubs found in the snapshot.
   static void LogCodeObject(Object* code_object);
+  // Used for logging callback entry points to be able to reveal their
+  // names in call stacks when information about native code exports is
+  // inaccessible.
+  static void LogCallbacks();
 
  private: