Prefer to forward-declare GraphicsContext in headers.

Source/web/PageOverlay.cpp

 /*
  * Copyright (C) 2011 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:
  *
  * 1. Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *
@@ skipping 13 matching lines @@
  * 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.
  */
 
 #include "config.h"
 #include "web/PageOverlay.h"
 
 #include "core/frame/Settings.h"
 #include "core/page/Page.h"
+#include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/graphics/GraphicsLayerClient.h"
 #include "public/platform/WebLayer.h"
 #include "public/web/WebPageOverlay.h"
 #include "public/web/WebViewClient.h"
 #include "web/WebViewImpl.h"
 
 using namespace WebCore;
 
 namespace blink {
@@ skipping 114 matching lines @@
         // this is not on a critical codepath? In order to do so, we'd
         // have to take scrolling into account.
         const WebSize& size = m_viewImpl->size();
         WebRect damagedRect(0, 0, size.width, size.height);
         if (m_viewImpl->client())
             m_viewImpl->client()->didInvalidateRect(damagedRect);
     }
 }
 
 } // namespace blink