[tracing] Support ConvertableToTraceFormat argument type.

Drive-by: Use perfect forwarding for AddTraceEvent arguments.

BUG=406277

Committed: https://crrev.com/dcac49af485fe5d4c0027f153901435dbb29c232
Review-Url: https://codereview.chromium.org/2367603002
Cr-Original-Commit-Position: refs/heads/master@{#39742}
Cr-Commit-Position: refs/heads/master@{#39789}

include/libplatform/v8-tracing.h

@@ -9,6 +9,8 @@
 #include <memory>
 #include <vector>
 
+#include "include/v8-platform.h"
+
 namespace v8 {
 namespace platform {
 namespace tracing {
@@ -28,18 +30,21 @@ class TraceObject {
 
   TraceObject() {}
   ~TraceObject();
-  void Initialize(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,
+  void Initialize(
+      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);
   void UpdateDuration();
-  void InitializeForTesting(char phase, const uint8_t* category_enabled_flag,
-                            const char* name, const char* scope, uint64_t id,
-                            uint64_t bind_id, int num_args,
+  void InitializeForTesting(
+      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,
-                            int pid, int tid, int64_t ts, int64_t tts,
+      const uint64_t* arg_values,
+      std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables,
+      unsigned int flags, int pid, int tid, int64_t ts, int64_t tts,
       uint64_t duration, uint64_t cpu_duration);
 
   int pid() const { return pid_; }
@@ -56,6 +61,9 @@ class TraceObject {
   const char** arg_names() { return arg_names_; }
   uint8_t* arg_types() { return arg_types_; }
   ArgValue* arg_values() { return arg_values_; }
+  std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables() {
+    return arg_convertables_;
+  }
   unsigned int flags() const { return flags_; }
   int64_t ts() { return ts_; }
   int64_t tts() { return tts_; }
@@ -71,10 +79,12 @@ class TraceObject {
   const uint8_t* category_enabled_flag_;
   uint64_t id_;
   uint64_t bind_id_;
-  int num_args_;
+  int num_args_ = 0;
   const char* arg_names_[kTraceMaxNumArgs];
   uint8_t arg_types_[kTraceMaxNumArgs];
   ArgValue arg_values_[kTraceMaxNumArgs];
+  std::unique_ptr<v8::ConvertableToTraceFormat>
+      arg_convertables_[kTraceMaxNumArgs];
   char* parameter_copy_storage_ = nullptr;
   unsigned int flags_;
   int64_t ts_;
@@ -221,11 +231,13 @@ class TracingController {
   void Initialize(TraceBuffer* trace_buffer);
   const uint8_t* GetCategoryGroupEnabled(const char* category_group);
   static const char* GetCategoryGroupName(const uint8_t* category_enabled_flag);
-  uint64_t AddTraceEvent(char phase, const uint8_t* category_enabled_flag,
-                         const char* name, const char* scope, uint64_t id,
-                         uint64_t bind_id, int32_t num_args,
+  uint64_t AddTraceEvent(
+      char phase, const uint8_t* category_enabled_flag, const char* name,
+      const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
       const char** arg_names, const uint8_t* arg_types,
-                         const uint64_t* arg_values, unsigned int flags);
+      const uint64_t* arg_values,
+      std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables,
+      unsigned int flags);
   void UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
                                 const char* name, uint64_t handle);
 

include/v8-platform.h

@@ -7,6 +7,8 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <memory>
+#include <string>
 
 namespace v8 {
 
@@ -17,24 +19,38 @@ class Isolate;
  */
 class Task {
  public:
-  virtual ~Task() {}
+  virtual ~Task() = default;
 
   virtual void Run() = 0;
 };
 
-
 /**
-* An IdleTask represents a unit of work to be performed in idle time.
-* The Run method is invoked with an argument that specifies the deadline in
-* seconds returned by MonotonicallyIncreasingTime().
-* The idle task is expected to complete by this deadline.
-*/
+ * An IdleTask represents a unit of work to be performed in idle time.
+ * The Run method is invoked with an argument that specifies the deadline in
+ * seconds returned by MonotonicallyIncreasingTime().
+ * The idle task is expected to complete by this deadline.
+ */
 class IdleTask {
  public:
-  virtual ~IdleTask() {}
+  virtual ~IdleTask() = default;
   virtual void Run(double deadline_in_seconds) = 0;
 };
 
+/**
+ * The interface represents complex arguments to trace events.
+ */
+class ConvertableToTraceFormat {
+ public:
+  virtual ~ConvertableToTraceFormat() = default;
+
+  /**
+   * Append the class info to the provided |out| string. The appended
+   * data must be a valid JSON object. Strings must be properly quoted, and
+   * escaped. There is no processing applied to the content after it is
+   * appended.
+   */
+  virtual void AppendAsTraceFormat(std::string* out) const = 0;
+};
 
 /**
  * V8 Platform abstraction layer.
@@ -54,7 +70,7 @@ class Platform {
     kLongRunningTask
   };
 
-  virtual ~Platform() {}
+  virtual ~Platform() = default;
 
   /**
    * Gets the number of threads that are used to execute background tasks. Is
@@ -158,6 +174,25 @@ class Platform {
     return 0;
   }
 
+  /**
+   * Adds a trace event to the platform tracing system. This function call is
+   * usually the result of a TRACE_* macro from trace_event_common.h when
+   * tracing and the category of the particular trace are enabled. It is not
+   * advisable to call this function on its own; it is really only meant to be
+   * used by the trace macros. The returned handle can be used by
+   * UpdateTraceEventDuration to update the duration of COMPLETE events.
+   */
+  virtual uint64_t AddTraceEvent(
+      char phase, const uint8_t* category_enabled_flag, const char* name,
+      const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
+      const char** arg_names, const uint8_t* arg_types,
+      const uint64_t* arg_values,
+      std::unique_ptr<ConvertableToTraceFormat>* arg_convertables,
+      unsigned int flags) {
+    return AddTraceEvent(phase, category_enabled_flag, name, scope, id, bind_id,
+                         num_args, arg_names, arg_types, arg_values, flags);
+  }
+
   /**
    * Sets the duration field of a COMPLETE trace event. It must be called with
    * the handle returned from AddTraceEvent().

src/libplatform/default-platform.cc

@@ -178,16 +178,17 @@ double DefaultPlatform::MonotonicallyIncreasingTime() {
          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, unsigned int flags) {
+    const uint64_t* arg_values,
+    std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables,
+    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, flags);
+        arg_names, arg_types, arg_values, arg_convertables, flags);
   }
 
   return 0;

src/libplatform/default-platform.h

@@ -51,11 +51,12 @@ class DefaultPlatform : public Platform {
   const uint8_t* GetCategoryGroupEnabled(const char* name) override;
   const char* GetCategoryGroupName(
       const uint8_t* category_enabled_flag) 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, int32_t num_args,
+  uint64_t AddTraceEvent(
+      char phase, const uint8_t* category_enabled_flag, const char* name,
+      const char* scope, uint64_t id, uint64_t bind_id, int32_t 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;
   void UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
                                 const char* name, uint64_t handle) override;

src/libplatform/tracing/trace-object.cc

@@ -5,6 +5,7 @@
 #include "include/libplatform/v8-tracing.h"
 
 #include "base/trace_event/common/trace_event_common.h"
+#include "include/v8-platform.h"
 #include "src/base/platform/platform.h"
 #include "src/base/platform/time.h"
 
@@ -30,11 +31,13 @@ V8_INLINE static void CopyTraceObjectParameter(char** buffer,
   }
 }
 
-void TraceObject::Initialize(char phase, const uint8_t* category_enabled_flag,
-                             const char* name, const char* scope, uint64_t id,
-                             uint64_t bind_id, int num_args,
+void TraceObject::Initialize(
+    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) {
+    const uint64_t* arg_values,
+    std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables,
+    unsigned int flags) {
   pid_ = base::OS::GetCurrentProcessId();
   tid_ = base::OS::GetCurrentThreadId();
   phase_ = phase;
@@ -55,6 +58,8 @@ void TraceObject::Initialize(char phase, const uint8_t* category_enabled_flag,
     arg_names_[i] = arg_names[i];
     arg_values_[i].as_uint = arg_values[i];
     arg_types_[i] = arg_types[i];
+    if (arg_types[i] == TRACE_VALUE_TYPE_CONVERTABLE)
+      arg_convertables_[i] = std::move(arg_convertables[i]);
   }
 
   bool copy = !!(flags & TRACE_EVENT_FLAG_COPY);
@@ -107,8 +112,10 @@ void TraceObject::InitializeForTesting(
     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, int pid, int tid,
-    int64_t ts, int64_t tts, uint64_t duration, uint64_t cpu_duration) {
+    const uint64_t* arg_values,
+    std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables,
+    unsigned int flags, int pid, int tid, int64_t ts, int64_t tts,
+    uint64_t duration, uint64_t cpu_duration) {
   pid_ = pid;
   tid_ = tid;
   phase_ = phase;

src/libplatform/tracing/trace-writer.cc

@@ -7,6 +7,7 @@
 #include <cmath>
 
 #include "base/trace_event/common/trace_event_common.h"
+#include "include/v8-platform.h"
 #include "src/base/platform/platform.h"
 
 namespace v8 {
@@ -112,6 +113,12 @@ void JSONTraceWriter::AppendArgValue(uint8_t type,
   }
 }
 
+void JSONTraceWriter::AppendArgValue(ConvertableToTraceFormat* value) {
+  std::string arg_stringified;
+  value->AppendAsTraceFormat(&arg_stringified);
+  stream_ << arg_stringified;
+}
+
 JSONTraceWriter::JSONTraceWriter(std::ostream& stream) : stream_(stream) {
   stream_ << "{\"traceEvents\":[";
 }
@@ -143,11 +150,17 @@ void JSONTraceWriter::AppendTraceEvent(TraceObject* trace_event) {
   const char** arg_names = trace_event->arg_names();
   const uint8_t* arg_types = trace_event->arg_types();
   TraceObject::ArgValue* arg_values = trace_event->arg_values();
+  std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables =
+      trace_event->arg_convertables();
   for (int i = 0; i < trace_event->num_args(); ++i) {
     if (i > 0) stream_ << ",";
     stream_ << "\"" << arg_names[i] << "\":";
+    if (arg_types[i] == TRACE_VALUE_TYPE_CONVERTABLE) {
+      AppendArgValue(arg_convertables[i].get());
+    } else {
       AppendArgValue(arg_types[i], arg_values[i]);
     }
+  }
   stream_ << "}}";
   // TODO(fmeawad): Add support for Flow Events.
 }

src/libplatform/tracing/trace-writer.h

@@ -20,6 +20,7 @@ class JSONTraceWriter : public TraceWriter {
 
  private:
   void AppendArgValue(uint8_t type, TraceObject::ArgValue value);
+  void AppendArgValue(v8::ConvertableToTraceFormat*);
 
   std::ostream& stream_;
   bool append_comma_ = false;

src/libplatform/tracing/tracing-controller.cc

@@ -46,13 +46,15 @@ uint64_t TracingController::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) {
+    const uint64_t* arg_values,
+    std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables,
+    unsigned int flags) {
   uint64_t handle;
   TraceObject* trace_object = trace_buffer_->AddTraceEvent(&handle);
   if (trace_object) {
     trace_object->Initialize(phase, category_enabled_flag, name, scope, id,
                              bind_id, num_args, arg_names, arg_types,
-                             arg_values, flags);
+                             arg_values, arg_convertables, flags);
   }
   return handle;
 }

src/tracing/trace-event.h

@@ -6,6 +6,7 @@
 #define SRC_TRACING_TRACE_EVENT_H_
 
 #include <stddef.h>
+#include <memory>
 
 #include "base/trace_event/common/trace_event_common.h"
 #include "include/v8-platform.h"
@@ -120,8 +121,7 @@ enum CategoryGroupEnabledFlags {
 //                    const uint8_t* arg_types,
 //                    const uint64_t* arg_values,
 //                    unsigned int flags)
-#define TRACE_EVENT_API_ADD_TRACE_EVENT \
-  v8::internal::tracing::TraceEventHelper::GetCurrentPlatform()->AddTraceEvent
+#define TRACE_EVENT_API_ADD_TRACE_EVENT v8::internal::tracing::AddTraceEventImpl
 
 // Set the duration field of a COMPLETE trace event.
 // void TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(
@@ -454,6 +454,28 @@ class TraceStringWithCopy {
   const char* str_;
 };
 
+static V8_INLINE uint64_t AddTraceEventImpl(
+    char phase, const uint8_t* category_group_enabled, const char* name,
+    const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
+    const char** arg_names, const uint8_t* arg_types,
+    const uint64_t* arg_values, unsigned int flags) {
+  std::unique_ptr<ConvertableToTraceFormat> arg_convertables[2];
+  if (num_args > 0 && arg_types[0] == TRACE_VALUE_TYPE_CONVERTABLE) {
+    arg_convertables[0].reset(reinterpret_cast<ConvertableToTraceFormat*>(
+        static_cast<intptr_t>(arg_values[0])));
+  }
+  if (num_args > 1 && arg_types[1] == TRACE_VALUE_TYPE_CONVERTABLE) {
+    arg_convertables[1].reset(reinterpret_cast<ConvertableToTraceFormat*>(
+        static_cast<intptr_t>(arg_values[1])));
+  }
+  DCHECK(num_args <= 2);
+  v8::Platform* platform =
+      v8::internal::tracing::TraceEventHelper::GetCurrentPlatform();
+  return platform->AddTraceEvent(phase, category_group_enabled, name, scope, id,
+                                 bind_id, num_args, arg_names, arg_types,
+                                 arg_values, arg_convertables, flags);
+}
+
 // Define SetTraceValue for each allowed type. It stores the type and
 // value in the return arguments. This allows this API to avoid declaring any
 // structures so that it is portable to third_party libraries.
@@ -494,6 +516,19 @@ INTERNAL_DECLARE_SET_TRACE_VALUE(const TraceStringWithCopy&, as_string,
 #undef INTERNAL_DECLARE_SET_TRACE_VALUE
 #undef INTERNAL_DECLARE_SET_TRACE_VALUE_INT
 
+static V8_INLINE void SetTraceValue(ConvertableToTraceFormat* convertable_value,
+                                    unsigned char* type, uint64_t* value) {
+  *type = TRACE_VALUE_TYPE_CONVERTABLE;
+  *value = static_cast<uint64_t>(reinterpret_cast<intptr_t>(convertable_value));
+}
+
+template <typename T>
+static V8_INLINE typename std::enable_if<
+    std::is_convertible<T*, ConvertableToTraceFormat*>::value>::type
+SetTraceValue(std::unique_ptr<T> ptr, unsigned char* type, uint64_t* value) {
+  SetTraceValue(ptr.release(), type, value);
+}
+
 // These AddTraceEvent template
 // function is defined here instead of in the macro, because the arg_values
 // could be temporary objects, such as std::string. In order to store
@@ -506,36 +541,38 @@ static V8_INLINE uint64_t AddTraceEvent(char phase,
                                         uint64_t id, uint64_t bind_id,
                                         unsigned int flags) {
   return TRACE_EVENT_API_ADD_TRACE_EVENT(phase, category_group_enabled, name,
-                                         scope, id, bind_id, kZeroNumArgs, NULL,
-                                         NULL, NULL, flags);
+                                         scope, id, bind_id, kZeroNumArgs,
+                                         nullptr, nullptr, nullptr, flags);
 }
 
 template <class ARG1_TYPE>
 static V8_INLINE uint64_t AddTraceEvent(
     char phase, const uint8_t* category_group_enabled, const char* name,
     const char* scope, uint64_t id, uint64_t bind_id, unsigned int flags,
-    const char* arg1_name, const ARG1_TYPE& arg1_val) {
+    const char* arg1_name, ARG1_TYPE&& arg1_val) {
   const int num_args = 1;
-  uint8_t arg_types[1];
-  uint64_t arg_values[1];
-  SetTraceValue(arg1_val, &arg_types[0], &arg_values[0]);
+  uint8_t arg_type;
+  uint64_t arg_value;
+  SetTraceValue(std::forward<ARG1_TYPE>(arg1_val), &arg_type, &arg_value);
   return TRACE_EVENT_API_ADD_TRACE_EVENT(
       phase, category_group_enabled, name, scope, id, bind_id, num_args,
-      &arg1_name, arg_types, arg_values, flags);
+      &arg1_name, &arg_type, &arg_value, flags);
 }
 
 template <class ARG1_TYPE, class ARG2_TYPE>
 static V8_INLINE uint64_t AddTraceEvent(
     char phase, const uint8_t* category_group_enabled, const char* name,
     const char* scope, uint64_t id, uint64_t bind_id, unsigned int flags,
-    const char* arg1_name, const ARG1_TYPE& arg1_val, const char* arg2_name,
-    const ARG2_TYPE& arg2_val) {
+    const char* arg1_name, ARG1_TYPE&& arg1_val, const char* arg2_name,
+    ARG2_TYPE&& arg2_val) {
   const int num_args = 2;
   const char* arg_names[2] = {arg1_name, arg2_name};
   unsigned char arg_types[2];
   uint64_t arg_values[2];
-  SetTraceValue(arg1_val, &arg_types[0], &arg_values[0]);
-  SetTraceValue(arg2_val, &arg_types[1], &arg_values[1]);
+  SetTraceValue(std::forward<ARG1_TYPE>(arg1_val), &arg_types[0],
+                &arg_values[0]);
+  SetTraceValue(std::forward<ARG2_TYPE>(arg2_val), &arg_types[1],
+                &arg_values[1]);
   return TRACE_EVENT_API_ADD_TRACE_EVENT(
       phase, category_group_enabled, name, scope, id, bind_id, num_args,
       arg_names, arg_types, arg_values, flags);

test/cctest/libplatform/test-tracing.cc

@@ -35,7 +35,8 @@ TEST(TestTraceObject) {
   TraceObject trace_object;
   uint8_t category_enabled_flag = 41;
   trace_object.Initialize('X', &category_enabled_flag, "Test.Trace",
-                          "Test.Scope", 42, 123, 0, NULL, NULL, NULL, 0);
+                          "Test.Scope", 42, 123, 0, nullptr, nullptr, nullptr,
+                          nullptr, 0);
   CHECK_EQ('X', trace_object.phase());
   CHECK_EQ(category_enabled_flag, *trace_object.category_enabled_flag());
   CHECK_EQ(std::string("Test.Trace"), std::string(trace_object.name()));
@@ -44,6 +45,19 @@ TEST(TestTraceObject) {
   CHECK_EQ(0, trace_object.cpu_duration());
 }
 
+class ConvertableToTraceFormatMock : public v8::ConvertableToTraceFormat {
+ public:
+  explicit ConvertableToTraceFormatMock(int value) : value_(value) {}
+  void AppendAsTraceFormat(std::string* out) const override {
+    *out += "[" + std::to_string(value_) + "," + std::to_string(value_) + "]";
+  }
+
+ private:
+  int value_;
+
+  DISALLOW_COPY_AND_ASSIGN(ConvertableToTraceFormatMock);
+};
+
 class MockTraceWriter : public TraceWriter {
  public:
   void AppendTraceEvent(TraceObject* trace_event) override {
@@ -75,7 +89,8 @@ TEST(TestTraceBufferRingBuffer) {
     TraceObject* trace_object = ring_buffer->AddTraceEvent(&handles[i]);
     CHECK_NOT_NULL(trace_object);
     trace_object->Initialize('X', &category_enabled_flag, names[i].c_str(),
-                             "Test.Scope", 42, 123, 0, NULL, NULL, NULL, 0);
+                             "Test.Scope", 42, 123, 0, nullptr, nullptr,
+                             nullptr, nullptr, 0);
     trace_object = ring_buffer->GetEventByHandle(handles[i]);
     CHECK_NOT_NULL(trace_object);
     CHECK_EQ('X', trace_object->phase());
@@ -128,13 +143,13 @@ TEST(TestJSONTraceWriter) {
     TraceObject trace_object;
     trace_object.InitializeForTesting(
         'X', tracing_controller.GetCategoryGroupEnabled("v8-cat"), "Test0",
-        v8::internal::tracing::kGlobalScope, 42, 123, 0, NULL, NULL, NULL,
-        TRACE_EVENT_FLAG_HAS_ID, 11, 22, 100, 50, 33, 44);
+        v8::internal::tracing::kGlobalScope, 42, 123, 0, nullptr, nullptr,
+        nullptr, nullptr, TRACE_EVENT_FLAG_HAS_ID, 11, 22, 100, 50, 33, 44);
     writer->AppendTraceEvent(&trace_object);
     trace_object.InitializeForTesting(
         'Y', tracing_controller.GetCategoryGroupEnabled("v8-cat"), "Test1",
-        v8::internal::tracing::kGlobalScope, 43, 456, 0, NULL, NULL, NULL, 0,
-        55, 66, 110, 55, 77, 88);
+        v8::internal::tracing::kGlobalScope, 43, 456, 0, nullptr, nullptr,
+        nullptr, nullptr, 0, 55, 66, 110, 55, 77, 88);
     writer->AppendTraceEvent(&trace_object);
     tracing_controller.StopTracing();
   }
@@ -264,6 +279,14 @@ TEST(TestTracingControllerMultipleArgsAndCopy) {
     mm = "CHANGED";
     mmm = "CHANGED";
 
+    TRACE_EVENT_INSTANT1("v8", "v8.Test", TRACE_EVENT_SCOPE_THREAD, "a1",
+                         new ConvertableToTraceFormatMock(42));
+    std::unique_ptr<ConvertableToTraceFormatMock> trace_event_arg(
+        new ConvertableToTraceFormatMock(42));
+    TRACE_EVENT_INSTANT2("v8", "v8.Test", TRACE_EVENT_SCOPE_THREAD, "a1",
+                         std::move(trace_event_arg), "a2",
+                         new ConvertableToTraceFormatMock(123));
+
     tracing_controller.StopTracing();
   }
 
@@ -274,7 +297,7 @@ TEST(TestTracingControllerMultipleArgsAndCopy) {
   GetJSONStrings(all_names, trace_str, "\"name\"", "\"", "\"");
   GetJSONStrings(all_cats, trace_str, "\"cat\"", "\"", "\"");
 
-  CHECK_EQ(all_args.size(), 22);
+  CHECK_EQ(all_args.size(), 24);
   CHECK_EQ(all_args[0], "\"aa\":11");
   CHECK_EQ(all_args[1], "\"bb\":22");
   CHECK_EQ(all_args[2], "\"cc\":33");
@@ -303,6 +326,8 @@ TEST(TestTracingControllerMultipleArgsAndCopy) {
   CHECK_EQ(all_names[20], "INIT");
   CHECK_EQ(all_names[21], "INIT");
   CHECK_EQ(all_args[21], "\"mm1\":\"INIT\",\"mm2\":\"\\\"INIT\\\"\"");
+  CHECK_EQ(all_args[22], "\"a1\":[42,42]");
+  CHECK_EQ(all_args[23], "\"a1\":[42,42],\"a2\":[123,123]");
 
   i::V8::SetPlatformForTesting(old_platform);
 }

test/cctest/test-trace-event.cc

@@ -71,10 +71,12 @@ class MockTracingPlatform : public v8::Platform {
 
   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,
+  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);