Implement tracing interface for v8

src/libplatform/default-platform.h

Index: src/libplatform/default-platform.h
diff --git a/src/libplatform/default-platform.h b/src/libplatform/default-platform.h
index 94ef9c5055de333a85bc0245d46d8779c324f218..c1683b45bacd59e7c57ff06f6ca06b89fb571dff 100644
--- a/src/libplatform/default-platform.h
+++ b/src/libplatform/default-platform.h
@@ -44,6 +44,20 @@ class DefaultPlatform : public Platform {
                                           IdleTask* task) override;
   virtual bool IdleTasksEnabled(Isolate* isolate) override;
   double MonotonicallyIncreasingTime() override;
+  virtual const uint8_t* GetCategoryGroupEnabled(const char* name) override;
+  virtual const char* GetCategoryGroupName(
+      const uint8_t* categoryEnabledFlag) override;
+  virtual uint64_t AddTraceEvent(char phase, const uint8_t* categoryEnabledFlag,
+                                 const char* name, uint64_t id,
+                                 uint64_t context_id, uint64_t bind_id,
+                                 int32_t numArgs, const char** argNames,
+                                 const uint8_t* argTypes,
+                                 const uint64_t* argValues,
+                                 unsigned int flags) override;
+  virtual void UpdateTraceEventDuration(const uint8_t* categoryEnabledFlag,
+                                        const char* name,
+                                        uint64_t handle) override;
+
 
  private:
   static const int kMaxThreadPoolSize;