Add API to create a platform with a tracing controller

BUG=v8:6511

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Ie6b62df693d3b847837c071e1f985b7ce3b420c8
Reviewed-on: https://chromium-review.googlesource.com/548499Reviewed-by: Fadi Meawad <fmeawad@chromium.org>
Commit-Queue: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46227}

include/libplatform/libplatform.h

@@ -30,12 +30,15 @@ enum class MessageLoopBehavior : bool {
  * If |idle_task_support| is enabled then the platform will accept idle
  * tasks (IdleTasksEnabled will return true) and will rely on the embedder
  * calling v8::platform::RunIdleTasks to process the idle tasks.
+ * If |tracing_controller| is nullptr, the default platform will create a
+ * v8::platform::TracingController instance and use it.
  */
 V8_PLATFORM_EXPORT v8::Platform* CreateDefaultPlatform(
     int thread_pool_size = 0,
     IdleTaskSupport idle_task_support = IdleTaskSupport::kDisabled,
     InProcessStackDumping in_process_stack_dumping =
-        InProcessStackDumping::kEnabled);
+        InProcessStackDumping::kEnabled,
+    v8::TracingController* tracing_controller = nullptr);
 
 /**
  * Pumps the message loop for the given isolate.

src/libplatform/default-platform.cc

@@ -31,13 +31,16 @@ void PrintStackTrace() {
 
 v8::Platform* CreateDefaultPlatform(
     int thread_pool_size, IdleTaskSupport idle_task_support,
-    InProcessStackDumping in_process_stack_dumping) {
+    InProcessStackDumping in_process_stack_dumping,
+    v8::TracingController* tracing_controller) {
   if (in_process_stack_dumping == InProcessStackDumping::kEnabled) {
     v8::base::debug::EnableInProcessStackDumping();
   }
   DefaultPlatform* platform = new DefaultPlatform(idle_task_support);
   platform->SetThreadPoolSize(thread_pool_size);
   platform->EnsureInitialized();
+  if (tracing_controller != nullptr)
+    platform->SetTracingController(tracing_controller);
   return platform;
 }
 
@@ -73,11 +76,6 @@ DefaultPlatform::DefaultPlatform(IdleTaskSupport idle_task_support)
       idle_task_support_(idle_task_support) {}
 
 DefaultPlatform::~DefaultPlatform() {
-  if (tracing_controller_) {
-    tracing_controller_->StopTracing();
-    tracing_controller_.reset();
-  }
-
   base::LockGuard<base::Mutex> guard(&lock_);
   queue_.Terminate();
   if (initialized_) {
@@ -316,7 +314,7 @@ const char* DefaultPlatform::GetCategoryGroupName(
 }
 
 void DefaultPlatform::SetTracingController(
-    tracing::TracingController* tracing_controller) {
+    TracingController* tracing_controller) {
   tracing_controller_.reset(tracing_controller);
 }
 

src/libplatform/default-platform.h

@@ -27,10 +27,6 @@ class TaskQueue;
 class Thread;
 class WorkerThread;
 
-namespace tracing {
-class TracingController;
-}
-
 class V8_PLATFORM_EXPORT DefaultPlatform : public NON_EXPORTED_BASE(Platform) {
  public:
   explicit DefaultPlatform(
@@ -72,7 +68,7 @@ class V8_PLATFORM_EXPORT DefaultPlatform : public NON_EXPORTED_BASE(Platform) {
       unsigned int flags) override;
   void UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
                                 const char* name, uint64_t handle) override;
-  void SetTracingController(tracing::TracingController* tracing_controller);
+  void SetTracingController(TracingController* tracing_controller);
 
   void AddTraceStateObserver(TraceStateObserver* observer) override;
   void RemoveTraceStateObserver(TraceStateObserver* observer) override;
@@ -103,7 +99,7 @@ class V8_PLATFORM_EXPORT DefaultPlatform : public NON_EXPORTED_BASE(Platform) {
            std::priority_queue<DelayedEntry, std::vector<DelayedEntry>,
                                std::greater<DelayedEntry> > >
       main_thread_delayed_queue_;
-  std::unique_ptr<tracing::TracingController> tracing_controller_;
+  std::unique_ptr<TracingController> tracing_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultPlatform);
 };