Switch all buildbots to GN build

scripts/slave/recipes/pdfium.expected/win_skia_gyp.json

Index: scripts/slave/recipes/pdfium.expected/win_skia_gyp.json
diff --git a/scripts/slave/recipes/pdfium.expected/win_skia_gn.json b/scripts/slave/recipes/pdfium.expected/win_skia_gyp.json
similarity index 84%
rename from scripts/slave/recipes/pdfium.expected/win_skia_gn.json
rename to scripts/slave/recipes/pdfium.expected/win_skia_gyp.json
index cfaef55abbc53a58f6dc36286e74f651d7de9315..b3ce82b4d82d2c2dc598e26ad26982dab0dbb098 100644
--- a/scripts/slave/recipes/pdfium.expected/win_skia_gn.json
+++ b/scripts/slave/recipes/pdfium.expected/win_skia_gyp.json
@@ -7,7 +7,7 @@
       "--master",
       "client.pdfium",
       "--builder",
-      "windows_skia_gn",
+      "windows_skia_gyp",
       "--slave",
       "test_slave",
       "--spec",
@@ -55,27 +55,13 @@
     ],
     "cwd": "[SLAVE_BUILD]\\pdfium",
     "env": {
-      "GYP_CHROMIUM_NO_ACTION": "1",
-      "GYP_DEFINES": "pdf_enable_v8=1 pdf_enable_xfa=1 pdf_use_skia=1",
+      "GYP_DEFINES": "pdf_enable_v8=1 pdf_enable_xfa=1 pdf_use_skia=1 target_arch=x64",
       "PATH": "%(PATH)s;RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
-      "python",
-      "-u",
-      "[DEPOT_TOOLS]\\gn.py",
-      "--root=[SLAVE_BUILD]\\pdfium",
-      "gen",
-      "//out/Debug",
-      "--args=is_debug=true pdf_enable_v8=true pdf_enable_xfa=true pdf_use_skia=true pdf_is_standalone=true"
-    ],
-    "cwd": "[SLAVE_BUILD]\\pdfium",
-    "name": "gn gen"
-  },
-  {
-    "cmd": [
       "ninja",
       "-C",
       "[SLAVE_BUILD]\\pdfium\\out\\Debug"