(WIP) Use generator to generate externs for chrome.fileManagerPrivate API.

ui/file_manager/file_manager/background/js/volume_manager_util.js

Index: ui/file_manager/file_manager/background/js/volume_manager_util.js
diff --git a/ui/file_manager/file_manager/background/js/volume_manager_util.js b/ui/file_manager/file_manager/background/js/volume_manager_util.js
index a02ce6a989773d8f3a6efd9a5ff9c86a616af472..56d154549c01a58666c8af337b41e142860f7591 100644
--- a/ui/file_manager/file_manager/background/js/volume_manager_util.js
+++ b/ui/file_manager/file_manager/background/js/volume_manager_util.js
@@ -51,7 +51,8 @@ volumeManagerUtil.validateError = function(error) {
 
 /**
  * Builds the VolumeInfo data from VolumeMetadata.
- * @param {VolumeMetadata} volumeMetadata Metadata instance for the volume.
+ * @param {chrome.fileManagerPrivate.VolumeMetadata} volumeMetadata Metadata
+ *     instance for the volume.
  * @return {!Promise.<VolumeInfo>} Promise settled with the VolumeInfo instance.
  */
 volumeManagerUtil.createVolumeInfo = function(volumeMetadata) {
@@ -206,7 +207,7 @@ volumeManagerUtil.createVolumeInfo = function(volumeMetadata) {
  * Note that errorType and volumeType must be an element of fixed set of strings
  * to avoid sending dynamic strings to analytics.
  *
- * @param {VolumeMetadata} volumeMetadata
+ * @param {chrome.fileManagerPrivate.VolumeMetadata} volumeMetadata
  * @param {*} error
  */
 volumeManagerUtil.reportMountError = function(volumeMetadata, error) {