Introduce a CompilerDispatcherTracer and track how long jobs take

test/unittests/heap/gc-tracer-unittest.cc

 // Copyright 2014 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.
 
 #include <cmath>
 #include <limits>
 
 #include "src/globals.h"
 #include "src/heap/gc-tracer.h"
 #include "src/isolate.h"
 #include "test/unittests/test-utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace v8 {
 namespace internal {
 
 typedef TestWithContext GCTracerTest;
 
 TEST(GCTracer, AverageSpeed) {
-  RingBuffer<BytesAndDuration> buffer;
+  base::RingBuffer<BytesAndDuration> buffer;
   EXPECT_EQ(100 / 2,
             GCTracer::AverageSpeed(buffer, MakeBytesAndDuration(100, 2), 0));
   buffer.Push(MakeBytesAndDuration(100, 8));
   EXPECT_EQ(100 / 2,
             GCTracer::AverageSpeed(buffer, MakeBytesAndDuration(100, 2), 2));
   EXPECT_EQ(200 / 10,
             GCTracer::AverageSpeed(buffer, MakeBytesAndDuration(100, 2), 3));
   const int max_speed = 1024 * MB;
   buffer.Reset();
   buffer.Push(MakeBytesAndDuration(max_speed, 0.5));
@@ skipping 258 matching lines @@
   // Switch to incremental MC.
   tracer->current_.type = GCTracer::Event::INCREMENTAL_MARK_COMPACTOR;
   tracer->Stop(MARK_COMPACTOR);
   EXPECT_DOUBLE_EQ((4000000.0 / 400 + 1000.0 / 2000) / 2,
                    static_cast<double>(
                        tracer->IncrementalMarkingSpeedInBytesPerMillisecond()));
 }
 
 }  // namespace internal
 }  // namespace v8