Add GN files for src/win8.

Review URL: https://codereview.chromium.org/796903004

Cr-Commit-Position: refs/heads/master@{#312036}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index 535ea981..d210d1c 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -650,8 +650,8 @@
       #"../chrome_elf/chrome_elf.gyp:chrome_elf_constants",  TODO(GYP)
       #"../chrome_elf/chrome_elf.gyp:dll_hash",  TODO(GYP)
       #"../google_update/google_update.gyp:google_update",  TODO(GYP)
-      #"../ui/metro_viewer/metro_viewer.gyp:metro_viewer_messages",  TODO(GYP)
-      #"../win8/win8.gyp:metro_viewer",  TODO(GYP)
+      "//ui/metro_viewer",
+      "//win8:metro_viewer",
     ]
   } else {
     # Non-Windows.