[gin] Support ConvertableToTraceFormat arguments for events coming from V8.

gin/v8_platform.cc

 // Copyright 2014 The Chromium 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 "gin/public/v8_platform.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/sys_info.h"
 #include "base/threading/worker_pool.h"
@@ skipping 79 matching lines @@
                                    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) {
+  std::unique_ptr<base::trace_event::ConvertableToTraceFormat> convertables[2];

[fmeawad, 2016/09/15 23:53:44]

Instead of the 2 if conditions, maybe a tiny for loop that we hope the compiler
will unroll?

[alph, 2016/09/15 23:58:14]

I doubt it will be able to unroll it as the num_args in not a compile time
constant.

+  if (num_args > 0 && arg_types[0] == TRACE_VALUE_TYPE_CONVERTABLE) {
+    convertables[0].reset(
+        reinterpret_cast<base::trace_event::ConvertableToTraceFormat*>(
+            arg_values[0]));
+  }
+  if (num_args > 1 && arg_types[1] == TRACE_VALUE_TYPE_CONVERTABLE) {
+    convertables[1].reset(
+        reinterpret_cast<base::trace_event::ConvertableToTraceFormat*>(
+            arg_values[1]));
+  }
   base::trace_event::TraceEventHandle handle =
       TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_BIND_ID(
           phase, category_enabled_flag, name, scope, id, bind_id, num_args,
-          arg_names, arg_types, (const long long unsigned int*)arg_values, NULL,
-          flags);
+          arg_names, arg_types, (const long long unsigned int*)arg_values,
+          convertables, flags);
   uint64_t result;
   memcpy(&result, &handle, sizeof(result));
   return result;
 }
 
 void V8Platform::UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
                                           const char* name,
                                           uint64_t handle) {
   base::trace_event::TraceEventHandle traceEventHandle;
   memcpy(&traceEventHandle, &handle, sizeof(handle));
@@ skipping 53 matching lines @@
     v8::Platform::TraceStateObserver* observer) {
   g_trace_state_dispatcher.Get().AddObserver(observer);
 }
 
 void V8Platform::RemoveTraceStateObserver(
     v8::Platform::TraceStateObserver* observer) {
   g_trace_state_dispatcher.Get().RemoveObserver(observer);
 }
 
 }  // namespace gin