Add events with custom timestamps and thread id to PPAPI dev tracing interface.

ppapi/api/dev/ppb_trace_event_dev.idl

 /* Copyright (c) 2012 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.
  */
 
 /**
  * This file defines the <code>PPB_Trace_Event</code> interface. It is meant
  * to be used in plugins as the API that trace macros from trace_event.h use.
  */
 
 label Chrome {
-  M25 = 0.1
+  M25 = 0.1,
+  M29 = 0.2
 };
 
 interface PPB_Trace_Event_Dev {
   /**
    * Gets a pointer to a character for identifying a category name in the
    * tracing system as well as for being able to early exit in client-side
    * tracing code.
    *
    * NB: This mem_t return value should technically be const, but return values
    * for Pepper IDL of mem_t type are not const.  The same is true for the arg
@@ skipping 13 matching lines @@
       [in] mem_t category_enabled,
       [in] cstr_t name,
       [in] uint64_t id,
       [in] uint32_t num_args,
       [in, size_as=num_args] str_t[] arg_names,
       [in, size_as=num_args] uint8_t[] arg_types,
       [in, size_as=num_args] uint64_t[] arg_values,
       [in] uint8_t flags);
 
   /**
+   * Version of the above interface that allows specifying a custom thread id
+   * and timestamp. This is useful for when tracing data cannot be registered
+   * in real time. For example, this could be used by storing timestamps
+   * internally and then registering the events retroactively.
+   */
+  [version=0.2]
+  void AddTraceEventWithThreadIdAndTimestamp(
+      [in] int8_t phase,
+      [in] mem_t category_enabled,
+      [in] cstr_t name,
+      [in] uint64_t id,
+      [in] int32_t thread_id,
+      [in] int64_t timestamp,

[dmichael (off chromium), 2013/06/25 22:19:27]

What do you think of a typedef or struct for the timestamp, to make the
connection between Now and this function more obvious and discourage providing
an int64_t some other way or doing arithmetic on the time.

e.g.
typedef int64_t PP_TraceEventTime;

[grosse, 2013/06/25 23:16:39]

Done.

+      [in] uint32_t num_args,
+      [in, size_as=num_args] str_t[] arg_names,
+      [in, size_as=num_args] uint8_t[] arg_types,
+      [in, size_as=num_args] uint64_t[] arg_values,
+      [in] uint8_t flags);
+
+  /**
+   * Get the current clock value. Since this uses the same function as the trace
+   * events use internally, it can be used to create events with explicit time
+   * stamps.
+   */
+  [version=0.2]
+  int64_t Now();
+
+  /**
    * Sets the thread name of the calling thread in the tracing system so it will
    * show up properly in chrome://tracing.
    */
   void SetThreadName([in] cstr_t thread_name);
 };