chore: bump chromium to 80.0.3987.51 (8-x-y) (#21738)

* chore: bump chromium in DEPS to 80.0.3987.49

* chore: bump chromium in DEPS to 80.0.3987.50

* chore: bump chromium in DEPS to 80.0.3987.51

DEPS

@@ -11,7 +11,7 @@ gclient_gn_args = [
 
 vars = {
   'chromium_version':
-    '80.0.3987.48',
+    '80.0.3987.51',
   'node_version':
     'v12.13.0',
   'nan_version':