Add new official.desktop Win PGO recipe builder.

tools/mb/mb_config.pyl

Index: tools/mb/mb_config.pyl
diff --git a/tools/mb/mb_config.pyl b/tools/mb/mb_config.pyl
index ad91f61bb9c7d00f6dbd4b00d1e991adac478ec4..b54b1aa2e66024ca04502a0e75603d54ba441419 100644
--- a/tools/mb/mb_config.pyl
+++ b/tools/mb/mb_config.pyl
@@ -456,6 +456,12 @@
         '1': 'official_chrome_pgo_phase_1',
         '2': 'official_chrome_pgo_phase_2',
       },
+      # TODO(mmoss): Remove this once official recipes are working and this
+      # just becomes the regular "win64-pgo" builder.
+      'win64-pgo-recipes': {
+        '1': 'official_chrome_pgo_phase_1',
+        '2': 'official_chrome_pgo_phase_2',
+      },
     },
 
     'official.desktop.continuous': {