Remove last dependencies on ui/base from ui/gfx

ui/gfx/canvas_paint_mac.h

Index: ui/gfx/canvas_paint_mac.h
diff --git a/ui/gfx/canvas_paint_mac.h b/ui/gfx/canvas_paint_mac.h
index 16d74109f6542bc74fd0af0e4ad3a857af59c53d..f3658c33f1f2c0d477621f1c9fc57a32f06d62ab 100644
--- a/ui/gfx/canvas_paint_mac.h
+++ b/ui/gfx/canvas_paint_mac.h
@@ -17,7 +17,7 @@ namespace gfx {
 // graphics context.  On construction, it will set up a context for painting
 // into, and on destruction, it will commit it to the current context.
 // Note: The created context is always inialized to (0, 0, 0, 0).
-class UI_EXPORT CanvasSkiaPaint : public Canvas {
+class GFX_EXPORT CanvasSkiaPaint : public Canvas {
  public:
   // This constructor assumes the result is opaque.
   explicit CanvasSkiaPaint(NSRect dirtyRect);