Add support for directory access to the file system API.

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 ab09e5a7ed712de85977c9f64878c93401628b9d..d5c8d202df542938165aeaf538194a2949f6671b 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -4147,6 +4147,9 @@ Make sure you do not expose any sensitive information.
       <message name="IDS_EXTENSION_PROMPT_WARNING_DOWNLOADS_OPEN" desc="Permission string for access to downloads.">
         Open downloaded files
       </message>
+      <message name="IDS_EXTENSION_PROMPT_WARNING_FILE_SYSTEM_DIRECTORY" desc="Permission string for access to directories and their contents.">
+        Access directories that you have opened in the application

[benwells, 2013/08/27 09:05:06]

This doesn't seem strong enough. For now let's include words to the effect of
'recursively', such as 'Access directories that you open, and all files and
folders those directories contain.'

[Sam McNally, 2013/08/28 05:44:25]

Done.

+      </message>
       <message name="IDS_EXTENSION_PROMPT_WARNING_FILE_SYSTEM_WRITE" desc="Permission string for write access to the file system.">
         Write to files that you have opened in the application

[benwells, 2013/08/27 09:05:06]

Hmm - we should merge these warnings together. Is that possible with the current
system?

[Matt Giuca, 2013/08/28 00:37:42]

I think it will take some work (but note that my suggestion also takes work).

I think we should either merge them, or do my suggestion of making the directory
warning message different depending on whether files are writable. My concern
with merging them is that the directory access one won't look much scarier than
the normal file one. If there are two warnings then maybe you are more likely to
notice the directory one.

       </message>