Revert of [tracing] Support ConvertableToTraceFormat argument type.

src/libplatform/default-platform.cc

 // Copyright 2013 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 "src/libplatform/default-platform.h"
 
 #include <algorithm>
 #include <queue>
 
 #include "src/base/logging.h"
@@ skipping 160 matching lines @@
 
 
 bool DefaultPlatform::IdleTasksEnabled(Isolate* isolate) { return false; }
 
 
 double DefaultPlatform::MonotonicallyIncreasingTime() {
   return base::TimeTicks::HighResolutionNow().ToInternalValue() /
          static_cast<double>(base::Time::kMicrosecondsPerSecond);
 }
 
+
 uint64_t DefaultPlatform::AddTraceEvent(
     char phase, const uint8_t* category_enabled_flag, const char* name,
     const char* scope, uint64_t id, uint64_t bind_id, int num_args,
     const char** arg_names, const uint8_t* arg_types,
-    const uint64_t* arg_values,
-    std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables,
-    unsigned int flags) {
+    const uint64_t* arg_values, unsigned int flags) {
   if (tracing_controller_) {
     return tracing_controller_->AddTraceEvent(
         phase, category_enabled_flag, name, scope, id, bind_id, num_args,
-        arg_names, arg_types, arg_values, arg_convertables, flags);
+        arg_names, arg_types, arg_values, flags);
   }
 
   return 0;
 }
 
 void DefaultPlatform::UpdateTraceEventDuration(
     const uint8_t* category_enabled_flag, const char* name, uint64_t handle) {
   if (tracing_controller_) {
     tracing_controller_->UpdateTraceEventDuration(category_enabled_flag, name,
                                                   handle);
@@ skipping 19 matching lines @@
     tracing::TracingController* tracing_controller) {
   tracing_controller_ = tracing_controller;
 }
 
 size_t DefaultPlatform::NumberOfAvailableBackgroundThreads() {
   return static_cast<size_t>(thread_pool_size_);
 }
 
 }  // namespace platform
 }  // namespace v8