Add RAIL tracing category to Chrome tracing.

cc/debug/benchmark_instrumentation.cc

 // Copyright 2013 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.
 
 #include "base/trace_event/trace_event.h"
 #include "cc/debug/benchmark_instrumentation.h"
 
 namespace cc {
 namespace benchmark_instrumentation {
 
 // Please do not change the trace events in this file without updating
 // tools/perf/measurements/rendering_stats.py accordingly.
 // The benchmarks search for events and their arguments by name.
 
 void IssueImplThreadRenderingStatsEvent(const RenderingStats& stats) {
-  TRACE_EVENT_INSTANT1("benchmark",
-                       "BenchmarkInstrumentation::ImplThreadRenderingStats",
-                       TRACE_EVENT_SCOPE_THREAD,
-                       "data", stats.AsTraceableData());
+  TRACE_EVENT_INSTANT1(
+      "benchmark,rail", "BenchmarkInstrumentation::ImplThreadRenderingStats",
+      TRACE_EVENT_SCOPE_THREAD, "data", stats.AsTraceableData());
 }
 
 void IssueDisplayRenderingStatsEvent() {
   std::unique_ptr<base::trace_event::TracedValue> record_data(
       new base::trace_event::TracedValue());
   record_data->SetInteger("frame_count", 1);
   TRACE_EVENT_INSTANT1(
       "benchmark", "BenchmarkInstrumentation::DisplayRenderingStats",
       TRACE_EVENT_SCOPE_THREAD, "data", std::move(record_data));
 }
 
 }  // namespace benchmark_instrumentation
 }  // namespace cc