This is UI side unreadable device support.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 437f56538ed127278286f16e549309e5b40419d2..7be82a556a41867f81bbc651f0167c0ebd04beef 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -9143,6 +9143,12 @@ Keep your key file in a safe place. You will need it to create new versions of y
        Are you sure you want to delete $1 items?
      </message>
 
+      <message name="IDS_FILE_BROWSER_UNKNOWN_FILESYSTEM_WARNING" desc="Displayed when device contents cannot be read because filesystem is unknown.">
+        This device cannot be opened, because its filesystem was not recognised.

[rginda, 2011/08/23 20:23:30]

No comma, and use recognized (-ised is the British variant)

[sidor, 2011/08/23 23:18:47]

Done.

+      </message>
+      <message name="IDS_FILE_BROWSER_UNSUPPORTED_FILESYSTEM_WARNING" desc="Displayed when device contents cannot be read because filesystem is unsupported.">
+        This device cannot be opened, because its filesystem is not supported on this machine.

[rginda, 2011/08/23 20:23:30]

No comma, and remove "on this machine".

[sidor, 2011/08/23 23:18:47]

Done.

+      </message>

[rginda, 2011/08/23 20:23:30]

Please add these strings to mock_chrome too.

[sidor, 2011/08/23 23:18:47]

Done.

       <message name="IDS_FILE_BROWSER_FORMATTING_WARNING" desc="Displayed when you attempt to format device.">
         Formatting the removable media is going to erase all data. Do you wish to continue?
       </message>