[Tracing] Make TracingCategoryObserver v8 internal.

This patch removes TracingCategoryObserver API and moves the creation of
observer inside platform initialization, by assuming that either
Platform::AddTraceStateObserver is implemented correctly to add observer to
tracing controller that implemented by embedders, or default tracing controller
has already been set up and attached to platform before
v8::V8::InitializePlatform is called.

BUG=v8:5590

Review-Url: https://codereview.chromium.org/2471583004
Cr-Commit-Position: refs/heads/master@{#40739}

BUILD.gn

@@ -852,7 +852,6 @@ v8_source_set("v8_base") {
     "include/v8-platform.h",
     "include/v8-profiler.h",
     "include/v8-testing.h",
-    "include/v8-tracing.h",
     "include/v8-util.h",
     "include/v8-version.h",
     "include/v8.h",

include/v8-tracing.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_V8_TRACING_H_
-#define V8_V8_TRACING_H_
-
-#include "v8.h"  // NOLINT(build/include)
-
-namespace v8 {
-namespace tracing {
-
-class V8_EXPORT TracingCategoryObserver {
- public:
-  enum Mode {
-    ENABLED_BY_NATIVE = 1 << 0,
-    ENABLED_BY_TRACING = 1 << 1,
-  };
-  static std::unique_ptr<TracingCategoryObserver> Create();
-  virtual ~TracingCategoryObserver() = default;
-
- protected:
-  TracingCategoryObserver() = default;
-};
-
-}  // namespace tracing
-}  // namespace v8
-
-#endif  // V8_V8_TRACING_H_

src/d8.cc

@@ -22,7 +22,6 @@
 
 #include "include/libplatform/libplatform.h"
 #include "include/libplatform/v8-tracing.h"
-#include "include/v8-tracing.h"
 #include "src/api.h"
 #include "src/base/cpu.h"
 #include "src/base/debug/stack_trace.h"
@@ -153,7 +152,6 @@ class PredictablePlatform : public Platform {
 
 
 v8::Platform* g_platform = NULL;
-std::unique_ptr<tracing::TracingCategoryObserver> g_tracing_category_observer;
 
 static Local<Value> Throw(Isolate* isolate, const char* message) {
   return isolate->ThrowException(
@@ -2823,6 +2821,21 @@ int Shell::Main(int argc, char* argv[]) {
                    ? new PredictablePlatform()
                    : v8::platform::CreateDefaultPlatform();
 
+  std::unique_ptr<platform::tracing::TracingController> tracing_controller;
+  if (options.trace_enabled) {
+    trace_file.open("v8_trace.json");
+    tracing_controller.reset(new platform::tracing::TracingController());
+    platform::tracing::TraceBuffer* trace_buffer =
+        platform::tracing::TraceBuffer::CreateTraceBufferRingBuffer(
+            platform::tracing::TraceBuffer::kRingBufferChunks,
+            platform::tracing::TraceWriter::CreateJSONTraceWriter(trace_file));
+    tracing_controller->Initialize(trace_buffer);
+    if (!i::FLAG_verify_predictable) {
+      platform::SetTracingController(g_platform, tracing_controller.get());
+      tracing_controller.release();
+    }
+  }
+
   v8::V8::InitializePlatform(g_platform);
   v8::V8::Initialize();
   if (options.natives_blob || options.snapshot_blob) {
@@ -2857,6 +2870,7 @@ int Shell::Main(int argc, char* argv[]) {
     create_params.create_histogram_callback = CreateHistogram;
     create_params.add_histogram_sample_callback = AddHistogramSample;
   }
+
   Isolate* isolate = Isolate::New(create_params);
   {
     Isolate::Scope scope(isolate);
@@ -2864,14 +2878,6 @@ int Shell::Main(int argc, char* argv[]) {
     PerIsolateData data(isolate);
 
     if (options.trace_enabled) {
-      trace_file.open("v8_trace.json");
-      platform::tracing::TracingController* tracing_controller =
-          new platform::tracing::TracingController();
-      platform::tracing::TraceBuffer* trace_buffer =
-          platform::tracing::TraceBuffer::CreateTraceBufferRingBuffer(
-              platform::tracing::TraceBuffer::kRingBufferChunks,
-              platform::tracing::TraceWriter::CreateJSONTraceWriter(
-                  trace_file));
       platform::tracing::TraceConfig* trace_config;
       if (options.trace_config) {
         int size = 0;
@@ -2884,14 +2890,6 @@ int Shell::Main(int argc, char* argv[]) {
         trace_config =
             platform::tracing::TraceConfig::CreateDefaultTraceConfig();
       }
-      tracing_controller->Initialize(trace_buffer);
-      if (!i::FLAG_verify_predictable) {
-        platform::SetTracingController(g_platform, tracing_controller);
-      }
-      g_tracing_category_observer = tracing::TracingCategoryObserver::Create();
-      g_platform->AddTraceStateObserver(
-          reinterpret_cast<Platform::TraceStateObserver*>(
-              g_tracing_category_observer.get()));
       tracing_controller->StartTracing(trace_config);
     }
 
@@ -2953,9 +2951,6 @@ int Shell::Main(int argc, char* argv[]) {
   isolate->Dispose();
   V8::Dispose();
   V8::ShutdownPlatform();
-  g_platform->RemoveTraceStateObserver(
-      reinterpret_cast<Platform::TraceStateObserver*>(
-          g_tracing_category_observer.get()));
   delete g_platform;
 
   return result;

src/tracing/tracing-category-observer.cc

@@ -4,7 +4,6 @@
 
 #include "src/tracing/tracing-category-observer.h"
 
-#include "include/v8.h"
 #include "src/flags.h"
 #include "src/tracing/trace-event.h"
 #include "src/v8.h"
@@ -12,18 +11,21 @@
 namespace v8 {
 namespace tracing {
 
-std::unique_ptr<TracingCategoryObserver> TracingCategoryObserver::Create() {
-  return std::unique_ptr<TracingCategoryObserver>(
-      new TracingCategoryObserverImpl());
-}
+TracingCategoryObserver* TracingCategoryObserver::instance_ = nullptr;
 
-TracingCategoryObserverImpl::TracingCategoryObserverImpl() {}
+void TracingCategoryObserver::SetUp() {
+  TracingCategoryObserver::instance_ = new TracingCategoryObserver();
+  v8::internal::V8::GetCurrentPlatform()->AddTraceStateObserver(
+      TracingCategoryObserver::instance_);
+}
 
-TracingCategoryObserverImpl::~TracingCategoryObserverImpl() {
-  OnTraceDisabled();
+void TracingCategoryObserver::TearDown() {
+  v8::internal::V8::GetCurrentPlatform()->RemoveTraceStateObserver(
+      TracingCategoryObserver::instance_);
+  delete TracingCategoryObserver::instance_;
 }
 
-void TracingCategoryObserverImpl::OnTraceEnabled() {
+void TracingCategoryObserver::OnTraceEnabled() {
   bool enabled = false;
   TRACE_EVENT_CATEGORY_GROUP_ENABLED(
       TRACE_DISABLED_BY_DEFAULT("v8.runtime_stats"), &enabled);
@@ -32,7 +34,7 @@ void TracingCategoryObserverImpl::OnTraceEnabled() {
   }
 }
 
-void TracingCategoryObserverImpl::OnTraceDisabled() {
+void TracingCategoryObserver::OnTraceDisabled() {
   v8::internal::FLAG_runtime_stats &= ~ENABLED_BY_TRACING;
 }
 

src/tracing/tracing-category-observer.h

@@ -6,20 +6,30 @@
 #define V8_TRACING_TRACING_CATEGORY_OBSERVER_H_
 
 #include "include/v8-platform.h"
-#include "include/v8-tracing.h"
+#include "src/base/lazy-instance.h"
 
 namespace v8 {
 namespace tracing {
 
-class TracingCategoryObserverImpl : public TracingCategoryObserver,
-                                    public Platform::TraceStateObserver {
+class TracingCategoryObserver : public Platform::TraceStateObserver {
  public:
-  TracingCategoryObserverImpl();
-  ~TracingCategoryObserverImpl();
+  enum Mode {
+    ENABLED_BY_NATIVE = 1 << 0,
+    ENABLED_BY_TRACING = 1 << 1,
+  };
+
+  static void SetUp();
+  static void TearDown();
 
   // v8::Platform::TraceStateObserver
   void OnTraceEnabled() final;
   void OnTraceDisabled() final;
+
+  TracingCategoryObserver() {}
+  ~TracingCategoryObserver() {}
+
+ private:
+  static TracingCategoryObserver* instance_;
 };
 
 }  // namespace tracing

src/v8.cc

@@ -20,7 +20,7 @@
 #include "src/runtime-profiler.h"
 #include "src/snapshot/natives.h"
 #include "src/snapshot/snapshot.h"
-
+#include "src/tracing/tracing-category-observer.h"
 
 namespace v8 {
 namespace internal {
@@ -94,11 +94,13 @@ void V8::InitializePlatform(v8::Platform* platform) {
   CHECK(!platform_);
   CHECK(platform);
   platform_ = platform;
+  v8::tracing::TracingCategoryObserver::SetUp();
 }
 
 
 void V8::ShutdownPlatform() {
   CHECK(platform_);
+  v8::tracing::TracingCategoryObserver::TearDown();
   platform_ = NULL;
 }
 

src/v8.gyp

@@ -392,7 +392,6 @@
         '../include/v8-platform.h',
         '../include/v8-profiler.h',
         '../include/v8-testing.h',
-        '../include/v8-tracing.h',
         '../include/v8-util.h',
         '../include/v8-version.h',
         '../include/v8.h',