Media Galleries: Add a dropPermissionForMediaFileSystem() API.

chrome/common/extensions/api/media_galleries.idl

Index: chrome/common/extensions/api/media_galleries.idl
===================================================================
--- chrome/common/extensions/api/media_galleries.idl	(revision 261942)
+++ chrome/common/extensions/api/media_galleries.idl	(working copy)
@@ -57,6 +57,8 @@
       void ([instanceOf=DOMFileSystem] object[] mediaFileSystems,
             DOMString selectedFileSystemName);
 
+  callback ForgetMediaFileSystemCallback = void (boolean wasForgotten);

[vandebo (ex-Chrome), 2014/04/07 16:01:01]

Is there a usecase for this?  If we can't think of one, lets leave it out until
we find one.  It'd be easy to add in later.

[Lei Zhang, 2014/04/07 22:32:04]

Success is not guaranteed, so there should be someway of letting the caller know
in case of a failure. The alarms API is similar.
https://developer.chrome.com/apps/alarms#method-clearAll

[Lei Zhang, 2014/04/08 02:05:11]

Also, since the API is asynchronous, the caller can't count on the call to have
completed until the callback has occurred.

+
   [inline_doc] dictionary MediaFileSystemMetadata {
     // The name of the file system.
     DOMString name;
@@ -141,6 +143,11 @@
     // gesture, the callback will run as though the user canceled.
     static void addUserSelectedFolder(AddUserFolderCallback callback);
 
+    // Give up access to a given media gallery.
+    static void forgetMediaFileSystem(

[vandebo (ex-Chrome), 2014/04/07 16:01:01]

I think 'cede' or 'drop' would be better than 'forget'

+        [instanceOf=DOMFileSystem] object mediaFileSystem,

[vandebo (ex-Chrome), 2014/04/07 16:01:01]

Should this take a FS object, or a gallery id?  You need a FS object to get to a
gallery id, but apps can persist the gallery id's that they have access to and
thus use them as keys for FS's in there UI.  i.e. if there's a long unused
removable device, the app may have the gallery id, but can't get the FS
object...

[Lei Zhang, 2014/04/07 22:32:04]

Done.

+	optional ForgetMediaFileSystemCallback callback);
+
     // Start a scan of the user's hard disks for directories containing media.
     // The scan may take a long time so progress and completion is communicated
     // by events. No permission is granted as a result of the scan, see