Define SK_DECLARE_LEGACY_CREATE_FROM_FONTDATA.

Skia is changing a few signatures to use smart pointers in its API. This
requires that Chromium be updated to match. This define will keep the
old API around while the Skia change is rolling into Chromium.

Review-Url: https://codereview.chromium.org/2341963004
Cr-Commit-Position: refs/heads/master@{#419048}

skia/BUILD.gn

@@ -48,7 +48,10 @@ config("skia_config") {
     "//third_party/skia/include/utils",
   ]
 
-  defines = [ "SK_IGNORE_DW_GRAY_FIX" ]
+  defines = [
+    "SK_IGNORE_DW_GRAY_FIX",
+    "SK_DECLARE_LEGACY_CREATE_FROM_FONTDATA",
+  ]
   defines += skia_for_chromium_defines
 
   defines += []