Introduce a CompilerDispatcherTracer and track how long jobs take

test/unittests/BUILD.gn

 # Copyright 2016 The V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("../../gni/v8.gni")
 
 v8_executable("unittests") {
   testonly = true
 
   sources = [
@@ skipping 11 matching lines @@
     "base/platform/condition-variable-unittest.cc",
     "base/platform/mutex-unittest.cc",
     "base/platform/platform-unittest.cc",
     "base/platform/semaphore-unittest.cc",
     "base/platform/time-unittest.cc",
     "base/sys-info-unittest.cc",
     "base/utils/random-number-generator-unittest.cc",
     "cancelable-tasks-unittest.cc",
     "char-predicates-unittest.cc",
     "compiler-dispatcher/compiler-dispatcher-job-unittest.cc",
+    "compiler-dispatcher/compiler-dispatcher-tracer-unittest.cc",
     "compiler/branch-elimination-unittest.cc",
     "compiler/checkpoint-elimination-unittest.cc",
     "compiler/common-operator-reducer-unittest.cc",
     "compiler/common-operator-unittest.cc",
     "compiler/compiler-test-utils.h",
     "compiler/control-equivalence-unittest.cc",
     "compiler/control-flow-optimizer-unittest.cc",
     "compiler/dead-code-elimination-unittest.cc",
     "compiler/diamond-unittest.cc",
     "compiler/effect-control-linearizer-unittest.cc",
@@ skipping 141 matching lines @@
 
     # Suppress warnings about importing locally defined symbols.
     if (is_component_build) {
       ldflags = [
         "/ignore:4049",
         "/ignore:4217",
       ]
     }
   }
 }