Some filebrowser bugs and retiring DiskChanged event in filebrowser

chrome/test/data/extensions/api_test/filebrowser_mount/test.html

Index: chrome/test/data/extensions/api_test/filebrowser_mount/test.html
===================================================================
--- chrome/test/data/extensions/api_test/filebrowser_mount/test.html	(revision 96398)
+++ chrome/test/data/extensions/api_test/filebrowser_mount/test.html	(working copy)
@@ -2,7 +2,7 @@
 // These have to be sync'd with extension_file_browser_private_apitest.cc
 var expectedVolume1 = {
   devicePath: 'device_path1',
-  mountPath: 'mount_path1/',
+  mountPath: 'mount_path1',
   systemPath: 'system_path1',
   filePath: 'file_path1',
   deviceLabel: 'device_label1',
@@ -17,7 +17,7 @@
 
 var expectedVolume2 = {
   devicePath: 'device_path2',
-  mountPath: 'mount_path2/',
+  mountPath: 'mount_path2',
   systemPath: 'system_path2',
   filePath: 'file_path2',
   deviceLabel: 'device_label2',
@@ -32,7 +32,7 @@
 
 var expectedVolume3 = {
   devicePath: 'device_path3',
-  mountPath: 'mount_path3/',
+  mountPath: 'mount_path3',
   systemPath: 'system_path3',
   filePath: 'file_path3',
   deviceLabel: 'device_label3',