Add private system extension API to get system update status

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 53dd61303a9d6f592470d516543f8a3227940c14..1e3b9b29a2f726e5009bc04cec2a523934fc601a 100644
--- a/chrome/common/extensions/api/extension_api.json
+++ b/chrome/common/extensions/api/extension_api.json
@@ -525,6 +525,50 @@
     ]
   },
   {
+    "namespace": "accessibilityPrivate",
+    "nodoc": true,
+    "platforms": ["chromeos"],
+    "types": [
+      {
+        "id": "UpdateStatus",
+        "type": "object",
+        "description": "Information about the system update.",
+        "properties": {
+          "state": {
+            "type": "string",
+            "enum": ["NotAvailable", "Updating", "NeedReboot"],
+            "description": "State of system update."

[dmazzoni, 2011/11/30 15:46:04]

Document briefly what these mean. (For example, make it clear that NeedReboot
means that the update has been downloaded and installed and will take effect as
soon as the user reboots.)

What if there's an error retrieving the update status? What happens?

[hashimoto, 2011/12/01 02:28:00]

Done.
Currently 'NotAvailable' is used for error state because the purpose of this API
is to notify users about available update, not about the detail of the update
mechanism.

+          },
+          "download_progress": {
+            "type": "number",
+            "description": "Pregress of download. [0.0 - 1.0]"

[dmazzoni, 2011/11/30 15:46:04]

Document that this will be 0 if the update is NotAvailable and 1 if the update
is NeedReboot.

[hashimoto, 2011/12/01 02:28:00]

Done.

+          }
+        }
+      }
+    ],
+    "functions": [
+      {
+        "name": "getUpdateStatus",
+        "type": "function",
+        "description": "Gets information about the system update.",
+        "parameters": [
+          {
+            "type": "function",
+            "name": "callback",
+            "parameters": [
+              {
+                "$ref": "UpdateStatus",
+                "name": "status",
+                "description": "Details of the system update"
+              }
+            ]
+          }
+        ]
+      }
+    ],
+    "events": []
+  },
+  {
     "namespace": "experimental.speechInput",
     "types": [
       {