win: pull gyp for gn generation

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index 68073d82b3b57c4290ecb6df25ba81e8da534798..3b3fb1af50e234343df286bf8c68c0dbcc697b76 100644
--- a/DEPS
+++ b/DEPS
@@ -156,11 +156,13 @@ deps_os = {
   },
   'win': {
     'src/third_party/nss':
-     Var('chromium_git') + '/chromium/deps/nss.git' + '@' + Var('nss_revision'),
+        Var('chromium_git') + '/chromium/deps/nss.git' + '@' + Var('nss_revision'),
     'src/third_party/bison':
-     Var('chromium_git') + '/chromium/deps/bison.git' + '@' + '083c9a45e4affdd5464ee2b224c2df649c6e26c3',
+        Var('chromium_git') + '/chromium/deps/bison.git' + '@' + '083c9a45e4affdd5464ee2b224c2df649c6e26c3',
     'src/third_party/gperf':
-     Var('chromium_git') + '/chromium/deps/gperf.git' + '@' + 'd892d79f64f9449770443fb06da49b5a1e5d33c1',
+        Var('chromium_git') + '/chromium/deps/gperf.git' + '@' + 'd892d79f64f9449770443fb06da49b5a1e5d33c1',
+    'src/tools/gyp':
+        Var('chromium_git') + '/external/gyp.git' + '@' + '487c0b6ae8b44932e45347211bca0e8387718436', # from svn revision 1998
   }
 }