Modify DeviceHandler to handle deviceFail event and add a message.

chrome/app/chromeos_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- ChromeOS-specific strings (included from generated_resources.grd).
      Everything in this file is wrapped in <if expr="chromeos">. -->
 <grit-part>
   <message name="IDS_EMPTY_STRING" desc="Empty string, exist only to make code generic. No translation required.">
   </message>
   <message name="IDS_CHROMEBOOK" desc="The localized name for Chromebook.">
     Chromebook
   </message>
   <message name="IDS_CHROMEBOX" desc="The localized name for Chromebox">
@@ skipping 3752 matching lines @@
   </message>
   <message name="IDS_DEVICE_UNSUPPORTED_MESSAGE" desc="Text of notification message which is shown when user inserts removable device (SD card, USB key...)">
    Sorry, the device <ph name="DEVICE_LABEL">$1<ex>My SD card</ex></ph> is not supported at this time.
   </message>
   <message name="IDS_DEVICE_UNSUPPORTED_DEFAULT_MESSAGE" desc="Text of notification message which is shown when user inserts removable device (SD card, USB key...)">
    Sorry, your external storage device is not supported at this time.
   </message>
   <message name="IDS_DEVICE_UNKNOWN_MESSAGE" desc="Text of notification message which is shown when user inserts removable device (SD card, USB key...)">
    Sorry, the device <ph name="DEVICE_LABEL">$1<ex>My SD card</ex></ph> could not be recognized.
   </message>
+  <message name="IDS_DEVICE_UNKNOWN_BUTTON_LABEL" desc="Text of a button label in a notification to format the device. If user clicks the button, Files.app opens and 
+  focus on unknown the device.">
+    Format this device.

[hirono, 2014/08/22 06:59:24]

Button label does not have a period. See #3759.

[iseki, 2014/08/25 04:49:25]

Done.

+  </message>
   <message name="IDS_DEVICE_UNKNOWN_DEFAULT_MESSAGE" desc="Text of notification message which is shown when user inserts removable device (SD card, USB key...)">
    Sorry, your external storage device could not be recognized.
   </message>
   <message name="IDS_MULTIPART_DEVICE_UNSUPPORTED_MESSAGE" desc="Text of notification message which is shown when user inserts removable device (SD card, USB key...)">
    Sorry, at least one partition on the device <ph name="DEVICE_LABEL">$1<ex>MySDcard</ex></ph> could not be mounted.
   </message>
   <message name="IDS_MULTIPART_DEVICE_UNSUPPORTED_DEFAULT_MESSAGE" desc="Text of notification message which is shown when user inserts removable device (SD card, USB key...)">
    Sorry, at least one partition on your external storage device could not be mounted.
   </message>
   <message name="IDS_EXTERNAL_STORAGE_DISABLED_MESSAGE" desc="Text of notification message which is shown when user inserts removable device but external storage is disabled by policy">
@@ skipping 1969 matching lines @@
   <message name="IDS_SET_TIME_BUTTON_CLOSE" desc="Text for the button to close the window.">
     Done
   </message>
   <message name="IDS_SET_TIME_DATE_LABEL" desc="Label for the date input element.">
     System date
   </message>
   <message name="IDS_SET_TIME_TIME_LABEL" desc="Label for the time input element.">
     System time
   </message>
 </grit-part>