Intorduce a separate preference for 'proxy server mode'

chrome/common/extensions/api/extension_api.json

Index: chrome/common/extensions/api/extension_api.json
diff --git a/chrome/common/extensions/api/extension_api.json b/chrome/common/extensions/api/extension_api.json
index 4e34632f0821db231540afd1a488c0ecac7c8830..1f4b5d2dc34e4151697dc6c786e91fd06b5c1ae6 100644
--- a/chrome/common/extensions/api/extension_api.json
+++ b/chrome/common/extensions/api/extension_api.json
@@ -3636,8 +3636,12 @@
         "description": "An object encapsulating a complete proxy configuration.",
         "properties": {
           "rules": {"$ref": "ProxyRules", "optional": true, "description": "The proxy rules describing this configuration."},
-          "autoDetect": {"type": "boolean", "optional": true, "description": "True if the proxy settings sbould be detected automatically."},
-          "pacScript": {"$ref": "PacScript", "optional": true, "description": "The proxy auto-config (PAC) script for this configuration."}
+          "pacScript": {"$ref": "PacScript", "optional": true, "description": "The proxy auto-config (PAC) script for this configuration."},
+          "mode": {
+            "type": "string",
+            "enum": ["disabled", "auto_detect", "manual", "system"],
+            "description": "'disabled' = Never use a proxy<br>'auto_detect' = Auto detect proxy settings<br>'manual' = Manually specify proxy settings<br>'system' = Use system proxy settings"
+          }
         }
       }
     ],