Introduce a CompilerDispatcherTracer and track how long jobs take

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

 // 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.
 
 #ifndef V8_COMPILER_DISPATCHER_COMPILER_DISPATCHER_JOB_H_
 #define V8_COMPILER_DISPATCHER_COMPILER_DISPATCHER_JOB_H_
 
 #include <memory>
 
 #include "src/base/macros.h"
 #include "src/handles.h"
 #include "testing/gtest/include/gtest/gtest_prod.h"
 
 namespace v8 {
 namespace internal {
 
+class CompilerDispatcherTracer;
 class CompilationInfo;
 class CompilationJob;
 class Isolate;
 class ParseInfo;
 class Parser;
 class SharedFunctionInfo;
 class String;
 class UnicodeCache;
 class Utf16CharacterStream;
 class Zone;
@@ skipping 47 matching lines @@
   bool FinalizeCompilingOnMainThread();
 
   // Transition from any state to kInitial and free all resources.
   void ResetOnMainThread();
 
  private:
   FRIEND_TEST(CompilerDispatcherJobTest, ScopeChain);
 
   CompileJobStatus status_ = CompileJobStatus::kInitial;
   Isolate* isolate_;
+  CompilerDispatcherTracer* tracer_;
   Handle<SharedFunctionInfo> shared_;  // Global handle.
   Handle<String> source_;        // Global handle.
   size_t max_stack_size_;
 
   // Members required for parsing.
   std::unique_ptr<UnicodeCache> unicode_cache_;
   std::unique_ptr<Zone> zone_;
   std::unique_ptr<Utf16CharacterStream> character_stream_;
   std::unique_ptr<ParseInfo> parse_info_;
   std::unique_ptr<Parser> parser_;
   std::unique_ptr<DeferredHandles> handles_from_parsing_;
 
   // Members required for compiling.
   std::unique_ptr<CompilationInfo> compile_info_;
   std::unique_ptr<CompilationJob> compile_job_;
 
   bool can_parse_on_background_thread_;
   bool can_compile_on_background_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(CompilerDispatcherJob);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_DISPATCHER_COMPILER_DISPATCHER_JOB_H_