Use VisibilityState enum and move WebPageVisibilityState to public/platform.

public/web/WebView.h

 /*
  * Copyright (C) 2009, 2010, 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 14 matching lines @@
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WebView_h
 #define WebView_h
 
 #include "../platform/WebColor.h"
+#include "../platform/WebPageVisibilityState.h"
 #include "../platform/WebString.h"
 #include "../platform/WebVector.h"
 #include "WebDragOperation.h"
 #include "WebHistoryCommitType.h"
 #include "WebHistoryItem.h"
-#include "WebPageVisibilityState.h"
 #include "WebWidget.h"
 
 namespace blink {
 
 class WebAXObject;
 class WebAutofillClient;
 class WebCredentialManagerClient;
 class WebDevToolsAgent;
 class WebDevToolsAgentClient;
 class WebDragData;
@@ skipping 436 matching lines @@
     // event gets generated/tested.
     virtual void forceNextWebGLContextCreationToFail() = 0;
 
 protected:
     ~WebView() {}
 };
 
 } // namespace blink
 
 #endif