Add UMA to measure font-display value

third_party/WebKit/Source/core/css/RemoteFontFaceSource.h

 // Copyright 2014 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.
 
 #ifndef RemoteFontFaceSource_h
 #define RemoteFontFaceSource_h
 
 #include "core/css/CSSFontFaceSource.h"
 #include "core/fetch/FontResource.h"
 #include "core/fetch/ResourcePtr.h"
 #include "wtf/Allocator.h"
 
 namespace blink {
 
 class FontLoader;
 
 enum FontDisplay {
     FontDisplayAuto,
     FontDisplayBlock,
     FontDisplaySwap,
     FontDisplayFallback,
-    FontDisplayOptional
+    FontDisplayOptional,
+    FontDisplayEnumMax
 };
 
 class RemoteFontFaceSource final : public CSSFontFaceSource, public FontResourceClient {
     WILL_BE_USING_PRE_FINALIZER(RemoteFontFaceSource, dispose);
 public:
     enum DisplayPeriod { BlockPeriod, SwapPeriod, FailurePeriod };
 
     explicit RemoteFontFaceSource(FontResource*, PassRefPtrWillBeRawPtr<FontLoader>, FontDisplay);
     ~RemoteFontFaceSource() override;
     void dispose();
@@ skipping 50 matching lines @@
     RefPtrWillBeMember<FontLoader> m_fontLoader;
     const FontDisplay m_display;
     DisplayPeriod m_period;
     FontLoadHistograms m_histograms;
     bool m_isInterventionTriggered;
 };
 
 } // namespace blink
 
 #endif