Remove last dependencies on ui/base from ui/gfx

ui/gfx/codec/png_codec.h

Index: ui/gfx/codec/png_codec.h
diff --git a/ui/gfx/codec/png_codec.h b/ui/gfx/codec/png_codec.h
index 86f170d359fd293b9ea49d9a32ac5e2e416e71c4..dbb86a5421a9a231fb216f7dffb038aab8b58343 100644
--- a/ui/gfx/codec/png_codec.h
+++ b/ui/gfx/codec/png_codec.h
@@ -23,7 +23,7 @@ class Size;
 // isn't as robust as would be required for a browser (see Decode() for more).
 // WebKit has its own more complicated PNG decoder which handles, among other
 // things, partially downloaded data.
-class UI_EXPORT PNGCodec {
+class GFX_EXPORT PNGCodec {
  public:
   enum ColorFormat {
     // 3 bytes per pixel (packed), in RGB order regardless of endianness.
@@ -43,7 +43,7 @@ class UI_EXPORT PNGCodec {
   };
 
   // Represents a comment in the tEXt ancillary chunk of the png.
-  struct UI_EXPORT Comment {
+  struct GFX_EXPORT Comment {
     Comment(const std::string& k, const std::string& t);
     ~Comment();