[CrosDisksClient] Determine device type from DeviceMediaType property sent by cros-disks.

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

 // Copyright (c) 2011 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.
 
 // These have to be sync'd with extension_file_browser_private_apitest.cc
 var expectedVolume1 = {
   devicePath: 'device_path1',
   mountPath: 'removable/mount_path1',
   systemPath: 'system_path1',
   filePath: 'file_path1',
   deviceLabel: 'device_label1',
   driveLabel: 'drive_label1',
-  deviceType: 'flash',
+  deviceType: 'usb',
   totalSize:  1073741824,
   isParent: false,
   isReadOnly: false,
   hasMedia: false,
   isOnBootDevice: false
 };
 
 var expectedVolume2 = {
   devicePath: 'device_path2',
   mountPath: 'mount_path2',
   mountPath: 'removable/mount_path2',
   systemPath: 'system_path2',
   filePath: 'file_path2',
   deviceLabel: 'device_label2',
   driveLabel: 'drive_label2',
-  deviceType: 'hdd',
+  deviceType: 'mobile',
   totalSize:  47723,
   isParent: true,
   isReadOnly: true,
   hasMedia: true,
   isOnBootDevice: true
 };
 
 var expectedVolume3 = {
   devicePath: 'device_path3',
   mountPath: 'mount_path3',
@@ skipping 73 matching lines @@
         "non_existent_device_path",
         chrome.test.callbackFail("Device path not found"));
   },
 
   function getVolumeMetadataBlankPath() {
     chrome.fileBrowserPrivate.getVolumeMetadata(
         "",
         chrome.test.callbackFail("Device path not found"));
   }
 ]);