[OBSOLETE] tracing v2: introduce TraceBufferWriter

components/tracing/proto/event.proto

+// Copyright 2016 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.
+
+syntax = "proto2";
+option optimize_for = LITE_RUNTIME;
+
+import "event_args_for_testing.proto";
+
+package tracing.proto;
+
+message Event {
+  enum Type {
+    COMPLETE = 1;
+    DURATION_BEGIN = 2;
+    DURATION_END = 3;
+  };
+
+  optional Type type = 1;
+
+  // Key of the category in the header dictionary (id -> string).
+  // This is an efficient (deduplicated) representation of the
+  // category strings (“v8”, “cc”, etc.)
+  optional uint32 category_id = 2;
+
+  // The same logic applies to name_id. The difference here is that
+  // in some rare cases (TRACE_STR_COPY) the name might be inlined
+  // in the event.
+  oneof name {
+    uint32 name_id = 3;
+    string name_str = 4;
+  }
+
+  // Override pid, only if different from the pid in the
+  // chunk header
+  optional uint32 process_id = 5;
+
+  // Override tid, only if different from the tid in the
+  // chunk header.
+  optional uint32 thread_id = 6;
+
+  // Omitted in most cases. Is used to disambiguate some events
+  // (e.g. counters). It is NOT required to be unique per trace,
+  // just unique per begin/end event pair.
+  optional uint64 id = 7;
+  optional string scope = 8;
+
+  // timestamp(NOW) - timestamp(chunk).
+  optional uint64 timestamp = 9;
+  optional uint64 thread_timestamp = 10;
+
+  // (thread) duration for COMPLETE (and similar) events.
+  optional uint64 duration = 11;
+  optional uint64 thread_duration = 12;
+
+  // All the possible event args type are listed here.
+  oneof args {
+    /*EventArgsSimple args_simple = 15;*/
+    tracing.proto.EventArgsForTesting args_for_testing = 16383;
+  }
+}