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 dfcb761a2b19c09a0dcb2c9613a404a3ff11525b..bbeade0f4425faf3a18fee50147f6f52b70bf8fc 100644
--- a/tools/mb/mb_config.pyl
+++ b/tools/mb/mb_config.pyl
@@ -453,6 +453,12 @@
         '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': {