(WIP) Implement V8 Tracing -- DO NOT LAND

gin/isolate_holder.cc

Index: gin/isolate_holder.cc
diff --git a/gin/isolate_holder.cc b/gin/isolate_holder.cc
index 334c0e0ee5130c6e1c081cb40c9f0541b06a2da9..e43f62a846f4dddabb8a188a24fab3d7fe75f50d 100644
--- a/gin/isolate_holder.cc
+++ b/gin/isolate_holder.cc
@@ -13,6 +13,7 @@
 #include "base/sys_info.h"
 #include "gin/array_buffer.h"
 #include "gin/debug_impl.h"
+#include "gin/event_tracer_impl.h"
 #include "gin/function_template.h"
 #include "gin/per_isolate_data.h"
 #include "gin/public/v8_platform.h"
@@ -169,6 +170,7 @@ void IsolateHolder::Initialize(ScriptMode mode,
   v8::V8::SetSnapshotDataBlob(&snapshot);
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
   v8::V8::Initialize();
+  InitV8EventTracer();
   v8_is_initialized = true;
 }