DevTools: do not report paint metrics under blink.user_timing category.

third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetector.cpp

 // 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.
 
 #include "core/paint/FirstMeaningfulPaintDetector.h"
 
 #include "core/css/FontFaceSet.h"
 #include "core/dom/TaskRunnerHelper.h"
 #include "core/paint/PaintTiming.h"
 #include "platform/Histogram.h"
@@ skipping 81 matching lines @@
   if (paint_timing_->FirstPaint() == 0.0)
     return;
 
   provisional_first_meaningful_paint_ = MonotonicallyIncreasingTime();
   next_paint_is_meaningful_ = false;
 
   if (network2_quiet_reached_)
     return;
 
   TRACE_EVENT_MARK_WITH_TIMESTAMP1(
-      "loading", "firstMeaningfulPaintCandidate",
+      "loading,devtools.timeline", "firstMeaningfulPaintCandidate",
       TraceEvent::ToTraceTimestamp(provisional_first_meaningful_paint_),
       "frame", GetDocument()->GetFrame());
   // Ignore the first meaningful paint candidate as this generally is the first
   // contentful paint itself.
   if (!seen_first_meaningful_paint_candidate_) {
     seen_first_meaningful_paint_candidate_ = true;
     return;
   }
   paint_timing_->SetFirstMeaningfulPaintCandidate(
       provisional_first_meaningful_paint_);
@@ skipping 109 matching lines @@
   } else if (first_meaningful_paint2_quiet_) {
     had_network_quiet_histogram.Count(kHadNetwork2Quiet);
   }
 }
 
 DEFINE_TRACE(FirstMeaningfulPaintDetector) {
   visitor->Trace(paint_timing_);
 }
 
 }  // namespace blink