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

[Matt Giuca, 2013/08/27 04:30:53]

What does "Access" mean? (I see you use similar wording to "Write to files"
below.) Is this for both read and write access at the same time? If it's just
read access, you should say "Read". If it's read and write, you should say "Read
and write". Also change the desc string.

Edit: Oh, I get it: it will be writable if you also have the write permission?

Well ideally I would want this to correctly state "read" or "read and write" but
that is some amount of work. (It means modifying the system that prints out
these messages to dynamically choose a version of this message, depending on
whether there is the separate write permission.) I think it's worth the effort,
so that our users are clear on what can be done with the directories. But not in
this CL.

+      </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
       </message>