Moving GraphicsContext and dependencies from core to platform.

Source/platform/graphics/Canvas2DLayerBridge.h

Index: Source/platform/graphics/Canvas2DLayerBridge.h
diff --git a/Source/core/platform/graphics/Canvas2DLayerBridge.h b/Source/platform/graphics/Canvas2DLayerBridge.h
similarity index 93%
rename from Source/core/platform/graphics/Canvas2DLayerBridge.h
rename to Source/platform/graphics/Canvas2DLayerBridge.h
index 9cc266440117636cf5a7e903019ebcdd6c994ce4..af6047dd44c1af5788b751e6ef249c35ca4261cb 100644
--- a/Source/core/platform/graphics/Canvas2DLayerBridge.h
+++ b/Source/platform/graphics/Canvas2DLayerBridge.h
@@ -28,8 +28,9 @@
 
 #include "SkDeferredCanvas.h"
 #include "SkImage.h"
-#include "core/platform/graphics/GraphicsContext3D.h"
+#include "platform/PlatformExport.h"
 #include "platform/geometry/IntSize.h"
+#include "platform/graphics/GraphicsContext3D.h"
 #include "public/platform/WebExternalTextureLayer.h"
 #include "public/platform/WebExternalTextureLayerClient.h"
 #include "public/platform/WebExternalTextureMailbox.h"
@@ -46,7 +47,7 @@ namespace WebCore {
 class Canvas2DLayerBridge;
 class PassCanvas2DLayerBridgePtr;
 
-class Canvas2DLayerBridgePtr {
+class PLATFORM_EXPORT Canvas2DLayerBridgePtr {
 public:
     Canvas2DLayerBridgePtr() { }
     Canvas2DLayerBridgePtr(const PassRefPtr<Canvas2DLayerBridge>& ptr) { m_ptr = ptr; }
@@ -61,7 +62,7 @@ private:
     RefPtr<Canvas2DLayerBridge> m_ptr;
 };
 
-class Canvas2DLayerBridge : public blink::WebExternalTextureLayerClient, public SkDeferredCanvas::NotificationClient, public DoublyLinkedListNode<Canvas2DLayerBridge>, public RefCounted<Canvas2DLayerBridge> {
+class PLATFORM_EXPORT Canvas2DLayerBridge : public blink::WebExternalTextureLayerClient, public SkDeferredCanvas::NotificationClient, public DoublyLinkedListNode<Canvas2DLayerBridge>, public RefCounted<Canvas2DLayerBridge> {
     WTF_MAKE_NONCOPYABLE(Canvas2DLayerBridge);
 public:
     enum OpacityMode {