Add a flag for printf debugging the compiler dispatcher

src/compiler-dispatcher/compiler-dispatcher-job.h

Index: src/compiler-dispatcher/compiler-dispatcher-job.h
diff --git a/src/compiler-dispatcher/compiler-dispatcher-job.h b/src/compiler-dispatcher/compiler-dispatcher-job.h
index 0bd450164a765da3a5a4f1369d66f84596836697..43978b8276d86e0782f8003afba8a5e4897963c7 100644
--- a/src/compiler-dispatcher/compiler-dispatcher-job.h
+++ b/src/compiler-dispatcher/compiler-dispatcher-job.h
@@ -86,6 +86,10 @@ class V8_EXPORT_PRIVATE CompilerDispatcherJob {
   // Estimate how long the next step will take using the tracer.
   double EstimateRuntimeOfNextStepInMs() const;
 
+  // Even though the name does not imply this, ShortPrint() must only be invoked
+  // on the main thread.
+  void ShortPrint();
+
  private:
   FRIEND_TEST(CompilerDispatcherJobTest, ScopeChain);
 
@@ -111,6 +115,8 @@ class V8_EXPORT_PRIVATE CompilerDispatcherJob {
   bool can_parse_on_background_thread_;
   bool can_compile_on_background_thread_;
 
+  bool trace_compiler_dispatcher_jobs_;
+
   DISALLOW_COPY_AND_ASSIGN(CompilerDispatcherJob);
 };