Make GN's "check" run cleanly.

skia/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 if (cpu_arch == "arm") {
   import("//build/config/arm.gni")
 }
 
@@ skipping 353 matching lines @@
       "//third_party/skia/src/opts/SkBlurImage_opts_SSE2.cpp",
       "//third_party/skia/src/opts/SkMorphology_opts_SSE2.cpp",
       "//third_party/skia/src/opts/SkUtils_opts_SSE2.cpp",
       "//third_party/skia/src/opts/SkXfermode_opts_SSE2.cpp",
 
       # SSE 3
       "//third_party/skia/src/opts/SkBitmapProcState_opts_SSSE3.cpp",
 
       # Chrome-specific.
       "ext/convolver_SSE2.cc",
+
+      # These are header files used by this target from the skia one above.
+      "ext/convolver.h",
+      "//third_party/skia/include/core/SkTypes.h",
     ]
 
     if (is_linux || is_mac) {
       cflags = [ "-mssse3" ]  # Note third 's'.
     }
   } else {
     assert(false, "Need to port ARM/MIPS stuff from skia_library_opts.gyp")
   }
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [
     ":skia_config",
     "//build/config/compiler:no_chromium_code"
   ]
 
-  # TODO(brettw) uncomment when visibility is supported.
-  #visibility = ":skia"
+  deps = [
+    "//base",
+  ]
+
+  visibility = ":skia"
 }