Add a data source field for volumes.

chrome/common/extensions/api/file_system_provider.idl

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Use the <code>chrome.fileSystemProvider</code> API to create file systems,
 // that can be accessible from the file manager on Chrome OS.
 [implemented_in="chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.h"]
 namespace fileSystemProvider {
   // Error codes used by providing extensions in response to requests as well
   // as in case of errors when calling methods of the API. For success, <code>
@@ skipping 23 matching lines @@
     READ,
     WRITE
   };
 
   // Type of a change detected on the observed directory.
   enum ChangeType {
     CHANGED,
     DELETED
   };
 
+  // Source of the file system data.
+  enum FileSystemSource {
+    // The file system is handling a file, eg. an archive file obtained via the
+    // <code>OnLaunched</code> event and the <code>file_handlers</code> manifest
+    // entry.
+    FILE,
+
+    // The file system contents are fetched from an external device, such as a
+    // USB device, but not via <code>file_handlers</code>.
+    DEVICE,
+
+    // The file system is network based. The contents are obtained from another
+    // server or local network. Eg. cloud services.
+    NETWORK
+  };
+
   // Represents metadata of a file or a directory.
   dictionary EntryMetadata {
     // True if it is a directory.
     boolean isDirectory;
 
     // Name of this entry (not full path name). Must not contain '/'. For root
     // it must be empty.
     DOMString name;
 
     // File size in bytes.
@@ skipping 48 matching lines @@
     // of the file system (such as creating, deleting or writing to files).
     boolean writable;
 
     // The maximum number of files that can be opened at once. If 0, then not
     // limited.
     long openedFilesLimit;
 
     // List of currently opened files.
     OpenedFile[] openedFiles;
 
+    // Source of the file system data.
+    FileSystemSource? source;
+
     // Whether the file system supports the <code>tag</code> field for observing
     // directories.
     [nodoc] boolean? supportsNotifyTag;
 
     // List of watchers.
     [nodoc] Watcher[] watchers;
   };
 
   // Options for the <code>mount()</code> method.
   dictionary MountOptions {
     // The string indentifier of the file system. Must be unique per each
     // extension.
     DOMString fileSystemId;
 
     // A human-readable name for the file system. 
     DOMString displayName;
 
     // Whether the file system supports operations which may change contents
     // of the file system (such as creating, deleting or writing to files).
     boolean? writable;
 
     // The maximum number of files that can be opened at once. If not specified,
     // or 0, then not limited.
     long? openedFilesLimit;
 
+    // Source of the file system data.
+    FileSystemSource? source;
+
     // Whether the file system supports the <code>tag</code> field for observed
     // directories. Required in order to enable the internal cache.
     [nodoc] boolean? supportsNotifyTag;
   };
 
   // Options for the <code>unmount()</code> method.
   dictionary UnmountOptions {
     // The identifier of the file system to be unmounted.
     DOMString fileSystemId;
   };
@@ skipping 297 matching lines @@
   callback ResultCallback = void();
 
   interface Functions {
     // Mounts a file system with the given <code>fileSystemId</code> and <code>
     // displayName</code>. <code>displayName</code> will be shown in the left
     // panel of Files.app. <code>displayName</code> can contain any characters
     // including '/', but cannot be an empty string. <code>displayName</code>
     // must be descriptive but doesn't have to be unique. The <code>fileSystemId
     // </code> must not be an empty string.
     //
+    // Depending on the type of the file system being mounted, the <code>source
+    // </code> option must be set apprioprietly. 

[benwells, 2015/04/09 07:32:12]

Nit: Spelling of appropriately.

[mtomasz, 2015/04/09 12:42:36]

Done.

+    //
     // In case of an error, <code>chrome.runtime.lastError</code> will be set
     // will a corresponding error code.
     static void mount(MountOptions options,
                       optional ResultCallback callback);
 
     // Unmounts a file system with the given <code>fileSystemId</code>. It
     // must be called after <code>onUnmountRequested</code> is invoked. Also,
     // the providing extension can decide to perform unmounting if not requested
     // (eg. in case of lost connection, or a file error).
     //
@@ skipping 167 matching lines @@
 
     // Raised when the watcher should be removed. If an error occurs, then
     // <code>errorCallback</code> must be called.
     [maxListeners=1, nodoc] static void onRemoveWatcherRequested(
       RemoveWatcherRequestedOptions options,
       ProviderSuccessCallback successCallback,
       ProviderErrorCallback errorCallback);
   };
 };