Implement systemInfo.storage.onChanged event

chrome/common/extensions/api/experimental_system_info_storage.idl

Index: chrome/common/extensions/api/experimental_system_info_storage.idl
diff --git a/chrome/common/extensions/api/experimental_system_info_storage.idl b/chrome/common/extensions/api/experimental_system_info_storage.idl
index 13ed295ad85680c962d6bbd15ee947ba84792429..dd851555f18a149aeb6381c8a0778e0a223e0020 100644
--- a/chrome/common/extensions/api/experimental_system_info_storage.idl
+++ b/chrome/common/extensions/api/experimental_system_info_storage.idl
@@ -32,8 +32,21 @@ namespace experimental.systemInfo.storage {
     double availableCapacity;
   };
 
+  // EventOption is used to filter the free space event. Only the conditions
+  // required by EventOption are both satisfied, the free space change event
+  // gets fired.
+  dictionary EventOption {
+    // The ID of storage unit being watched.
+    DOMString id;
+    // The minimum value of the available capacity changed to fire free space
+    // change event, in bytes. Default value is 1024 bytes (1K).
+    long? changeThreshold;
+  };
+
   callback StorageInfoCallback = void (StorageUnitInfo[] info);
 
+  callback StorageChangeCallback = void (StorageChangeInfo changeInfo);
+
   interface Functions {
     // Get the storage information from the system. The argument passed to the
     // callback is an array of StorageUnitInfo objects.
@@ -41,9 +54,31 @@ namespace experimental.systemInfo.storage {
   };
 
   interface Events {
-    // Fired when the storage information is updated.
-    // |info|   : The changed information for the specified storage unit
-    static void onAvailableCapacityChanged(StorageChangeInfo info);
+    // Fired when the storage free space is changed. To register an event
+    // listener for storage change event, a variant of the general <code>
+    // addListener()<code> function of <code>chrome.Event</code> is provided.
+    // In addtional to specifying a callback function, you have to specify

[benwells, 2012/12/11 04:40:40]

nit: addition

+    // an event option argument used to filter the event. 
+    //
+    // The 2 arguments to <code>addListener()</code> have the following
+    // definitions:
+    // <code>
+    //   chrome.experimental.systemInfo.storage.onChanged.addListener(
+    //     function callback, EventOption eventOption);
+    //   callback = function(StorageChangeInfo details);
+    // </code>
+    //
+    // Here's an example of listening <code>onChanged</code> event:
+    // <code>
+    //    chrome.experimental.systemInfo.storage.onChanged.addListener(
+    //         function(details) {}, {id: <id>, changeThreshold: 1000});
+    // </code>
+    // Where <code>id<code> parameter is the storage id returned from <code>
+    // chrome.experimental.systemInfo.get</code> calling, and <code>
+    // changeThreshold</code> means the minimum changed bytes of the free 
+    // space to trigger the event for the specified storage. Default change
+    // threshold is 1024 bytes.
+    static void onChanged(StorageChangeInfo info);
   };
  
 };