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

chrome/common/extensions/api/fileBrowserPrivate.json

 [
   {
     "namespace":"fileBrowserPrivate",
     "nodoc": "true",
     "types": [
       {
         "id": "FileBrowserTask",
         "type": "object",
         "description": "Represents information about available browser tasks. A task is an abstraction of an operation that the file browser can perform over a selected file set.",
         "properties": {
@@ skipping 19 matching lines @@
           "devicePath": {
             "type": "string",
             "description": "Disk volume device path."
           },
           "label": {
             "type": "string",
             "description": "Volume label."
           },
           "deviceType": {
             "type": "string",
-            "enum": ["flash", "hdd", "optical", "undefined"],
+            "enum": ["sd", "usb", "optical", "mobile", "unknown"],
             "description": "Device type."
           },
           "readOnly": {
             "type": "boolean",
             "description": "Flag that specifies if volume is mounted in read-only mode."
           },
           "totalSizeKB": {
             "type": "integer",
             "description": "Total disk volume size in KBs"
           }
@@ skipping 63 matching lines @@
           "deviceLabel": {
             "type": "string",
             "description": "Volume label."
           },
           "driveLabel": {
             "type": "string",
             "description": "Volume's disk label."
           },
           "deviceType": {
             "type": "string",
-            "enum": ["flash", "hdd", "optical", "undefined"],
+            "enum": ["usb", "sd", "optical", "mobile", "unknown"],
             "description": "Device type."
           },
           "isParent": {
             "type": "boolean",
             "description": "Flag that specifies if volume is a parent device."
           },
           "isReadOnly": {
             "type": "boolean",
             "description": "Flag that specifies if volume is mounted in read-only mode."
           },
@@ skipping 430 matching lines @@
           {
             "$ref": "FileWatchEvent",
             "name": "event",
             "description": "File watch event information."
           }
         ]
       }
     ]
   }
 ]