Add *explicit* keyword to avoid implicit type conversion

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"
 
 namespace WebCore {
 
 class RemoteFontFaceSource : public CSSFontFaceSource, public FontResourceClient {
 public:
-    RemoteFontFaceSource(FontResource*);
+    explicit RemoteFontFaceSource(FontResource*);
     virtual ~RemoteFontFaceSource();
 
     virtual FontResource* resource() OVERRIDE { return m_font.get(); }
     virtual bool isLoading() const OVERRIDE;
     virtual bool isLoaded() const OVERRIDE;
     virtual bool isValid() const OVERRIDE;
 
     void beginLoadIfNeeded();
     virtual bool ensureFontData();
 
@@ skipping 29 matching lines @@
         double m_fallbackPaintTime;
     };
 
     ResourcePtr<FontResource> m_font;
     FontLoadHistograms m_histograms;
 };
 
 } // namespace WebCore
 
 #endif