Implement tracing interface for v8

include/v8-platform.h

 // Copyright 2013 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.
 
 #ifndef V8_V8_PLATFORM_H_
 #define V8_V8_PLATFORM_H_
 
+#include <stdint.h>
+
 namespace v8 {
 
 class Isolate;
 
 /**
  * A Task represents a unit of work.
  */
 class Task {
  public:
   virtual ~Task() {}
@@ skipping 82 matching lines @@
   }
 
   /**
    * Monotonically increasing time in seconds from an arbitrary fixed point in
    * the past. This function is expected to return at least
    * millisecond-precision values. For this reason,
    * it is recommended that the fixed point be no further in the past than
    * the epoch.
    **/
   virtual double MonotonicallyIncreasingTime() = 0;
+
+  /**
+   * Get a pointer to the enabled state of the given trace category.
+   **/
+  virtual const uint8_t* GetCategoryGroupEnabled(const char* name) = 0;
+
+  /**
+   * Get the category group name of the given category_enabled_flags.
+   **/
+  virtual const char* GetCategoryGroupName(
+      const uint8_t* category_enabled_flag) = 0;
+
+  /**
+   * Add a trace event to the platform tracing system.

[Yang, 2015/11/19 09:30:32]

Can you add a comment about what this method returns? It seems unclear to me.

[fmeawad, 2015/11/20 22:22:20]

I have updated the description on all the methods.

+   **/
+  virtual uint64_t AddTraceEvent(
+      char phase, const uint8_t* category_enabled_flag, const char* name,
+      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) = 0;
+
+  /**
+   * Set the duration field of a COMPLETE trace event.
+   **/
+  virtual void UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
+                                        const char* name, uint64_t handle) = 0;
 };
 
 }  // namespace v8
 
 #endif  // V8_V8_PLATFORM_H_