Remove no-op Skia defines

These have all been deleted from the Skia codebase over the last
12 months or so.

Change-Id: Ib9c524ab0704ecb4ff9895b8d039fbbebb182976
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/128990
Auto-Submit: Kaylee Lubick <kjlubick@google.com>
Commit-Queue: Kaylee Lubick <kjlubick@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
diff --git a/skia/BUILD.gn b/skia/BUILD.gn
index 12b9185..682f85c 100644
--- a/skia/BUILD.gn
+++ b/skia/BUILD.gn
@@ -57,24 +57,8 @@
   defines = [
     "SK_ENCODE_PNG",
     "SK_USER_CONFIG_HEADER=\"../../skia/config/SkPdfiumUserConfig.h\"",
-    "SK_DISABLE_LEGACY_SKSURFACE_METHODS",
-    "SK_DISABLE_LEGACY_GRAPHITE_IMAGE_FACTORIES",
-    "SK_DISABLE_LEGACY_GRAPHITE_IMAGE_METHODS",
-    "SK_DISABLE_LEGACY_SKSURFACE_FACTORIES",
-    "SK_DISABLE_LEGACY_SKSURFACE_FLUSH",
-    "SK_DISABLE_LEGACY_SKSURFACE_AS_IMAGE",
-    "SK_DISABLE_LEGACY_SKSURFACE_DISPLAYLIST",
-    "SK_DISABLE_LEGACY_IMAGE_SUBSET_METHODS",
-    "SK_DISABLE_LEGACY_IMAGE_COLORSPACE_METHODS",
-    "SK_DISABLE_LEGACY_IMAGE_RELEASE_PROCS",
-    "SK_DISABLE_LEGACY_GL_BACKEND_SURFACE",
     "SK_DISABLE_LEGACY_INIT_DECODERS",
-    "SK_DISABLE_LEGACY_GRDIRECTCONTEXT_FLUSH",
-    "SK_DISABLE_LEGACY_GRDIRECTCONTEXT_BOOLS",
-    "SK_DISABLE_LEGACY_GL_GRDIRECTCONTEXT_FACTORIES",
     "SK_DISABLE_LEGACY_PNG_WRITEBUFFER",
-    "SK_SLUG_DISABLE_LEGACY_DESERIALIZE",
-    "SK_DISABLE_LEGACY_VK_GRDIRECTCONTEXT_FACTORIES",
   ]
 
   if (is_win) {