Added mount change notification callback: chrome.fileSystem.onChanged...

chrome/common/extensions/api/extension_api.json

 [
   {
     "namespace": "extension",
     "unprivileged": true,
     "types": [
       {
         "id": "MessageSender",
         "type": "object",
         "description": "An object containing information about the script context that sent a message or request.",
         "properties": {
@@ skipping 4482 matching lines @@
             "optional": "false",
             "parameters": [
               {
                 "type": "object",
                 "isInstanceOf": "DOMFileSystem"
               }
             ]
           }
         ]
       }
+    ],
+    "events": [
+      {
+        "name": "onChanged",
+        "type": "function",
+        "description": "Fired when underlying file system changes.",
+        "parameters": [
+          {
+            "type": "string",
+            "name": "fullPath",
+            "description": "Path of the filesystem directory entry that changed."
+          }
+        ]
+      }
     ]
   },
 
   {
     "namespace":"webstorePrivate",
     "nodoc": "true",
     "functions": [
       {
         "name": "install",
         "description": "Installs the extension corresponding to the given id",
@@ skipping 365 matching lines @@
           {
             "type": "integer",
             "name": "tabId",
             "description": "The id of the tab that was detached."
           }
         ]
       }
     ]
   }
 ]