Revert Revert 94812 - Formatting feature initial commit for ChromeOS Tree

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 6449 matching lines @@
             "parameters": [
               {
                 "name" : "mountPoints",
                 "type": "array",
                 "items": {"$ref": "MountPointInfo"},
                 "description": "The list of MountPointInfo representing mounted devices."
               }
             ]
           }
         ]
+      },
+      {
+        "name": "formatDevice",
+        "description": "Formats a mounted device",
+        "parameters": [
+          {
+            "name": "mountPath",
+            "type": "string",
+            "description": "Device's mount path."
+          }
+        ]
       }
     ],
     "events": [
       {
         "name": "onDiskChanged",
         "type": "function",
         "description": "Fired when disk mount/unmount event is detected.",
         "parameters": [
           {
             "$ref": "MountEvent",
@@ skipping 1036 matching lines @@
                 "description": "A string result code. The value is non-empty on success only in tests.",
                 "optional": "true"
               }
             ]
           }
         ]
       }
     ]
   }
 ]