Make ClientHintsPreferences class work like a class.

Source/core/fetch/ClientHintsPreferences.h

 // Copyright 2015 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 ClientHintsPreferences_h
 #define ClientHintsPreferences_h
 
 #include "core/CoreExport.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class ResourceFetcher;
 
-class ClientHintsPreferences {
+class CORE_EXPORT ClientHintsPreferences {
 public:
-    ClientHintsPreferences()
-        : m_shouldSendDPR(false)
-        , m_shouldSendResourceWidth(false)
-        , m_shouldSendViewportWidth(false)
-    {
-    }
+    ClientHintsPreferences();
 
-    void set(const ClientHintsPreferences& other)
-    {
-        m_shouldSendDPR = other.m_shouldSendDPR;
-        m_shouldSendResourceWidth = other.m_shouldSendResourceWidth;
-        m_shouldSendViewportWidth = other.m_shouldSendViewportWidth;
-    }
+    void updateFrom(const ClientHintsPreferences&);
+    void updateFromAcceptClientHintsHeader(const String& headerValue, ResourceFetcher*);
 
+    bool shouldSendDPR() const { return m_shouldSendDPR; }
     void setShouldSendDPR(bool should) { m_shouldSendDPR = should; }
+
+    bool shouldSendResourceWidth() const { return m_shouldSendResourceWidth; }
     void setShouldSendResourceWidth(bool should) { m_shouldSendResourceWidth = should; }
+
+    bool shouldSendViewportWidth() const { return m_shouldSendViewportWidth; }
     void setShouldSendViewportWidth(bool should) { m_shouldSendViewportWidth = should; }
-    bool shouldSendDPR() const { return m_shouldSendDPR; }
-    bool shouldSendResourceWidth() const { return m_shouldSendResourceWidth; }
-    bool shouldSendViewportWidth() const { return m_shouldSendViewportWidth; }
 
 private:
     bool m_shouldSendDPR;
     bool m_shouldSendResourceWidth;
     bool m_shouldSendViewportWidth;
 };
 
-CORE_EXPORT void handleAcceptClientHintsHeader(const String& headerValue, ClientHintsPreferences&, ResourceFetcher*);
 } // namespace blink
+
 #endif
-