[tracing] Support ConvertableToTraceFormat argument type.

test/cctest/test-trace-event.cc

 // Copyright 2015 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 <stdlib.h>
 #include <string.h>
 
 #include "src/v8.h"
 
 #include "src/list.h"
 #include "src/list-inl.h"
@@ skipping 53 matching lines @@
   bool IdleTasksEnabled(Isolate* isolate) override { return false; }
 
   bool PendingIdleTask() { return false; }
 
   void PerformIdleTask(double idle_time_in_seconds) {}
 
   bool PendingDelayedTask() { return false; }
 
   void PerformDelayedTask() {}
 
-  uint64_t 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,
-                         unsigned int flags) override {
+  uint64_t 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) override {
     MockTraceObject* to = new MockTraceObject(phase, std::string(name), id,
                                               bind_id, num_args, flags);
     trace_object_list_.Add(to);
     return 0;
   }
 
   void UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
                                 const char* name, uint64_t handle) override {}
 
   const uint8_t* GetCategoryGroupEnabled(const char* name) override {
@@ skipping 184 matching lines @@
   CHECK_EQ("Isolate", GET_TRACE_OBJECT(0)->name);
   CHECK_EQ(isolate_id, GET_TRACE_OBJECT(0)->id);
   CHECK_EQ(TRACE_EVENT_PHASE_COMPLETE, GET_TRACE_OBJECT(1)->phase);
   CHECK_EQ("e", GET_TRACE_OBJECT(1)->name);
   CHECK_EQ(TRACE_EVENT_PHASE_LEAVE_CONTEXT, GET_TRACE_OBJECT(2)->phase);
   CHECK_EQ("Isolate", GET_TRACE_OBJECT(2)->name);
   CHECK_EQ(isolate_id, GET_TRACE_OBJECT(2)->id);
 
   i::V8::SetPlatformForTesting(old_platform);
 }