Prevent duplicate webstore install requests being serviced.

chrome/common/extensions/api/webstore_private.json

Index: chrome/common/extensions/api/webstore_private.json
diff --git a/chrome/common/extensions/api/webstore_private.json b/chrome/common/extensions/api/webstore_private.json
index ebc26ceb68cac4a106abdb929084cce79b19a109..83fb48d4387edcdb545b0908edfb95bd28c326d9 100644
--- a/chrome/common/extensions/api/webstore_private.json
+++ b/chrome/common/extensions/api/webstore_private.json
@@ -124,7 +124,7 @@
               {
                 "name": "result",
                 "type": "string",
-                "description": "A string result code, which will be empty upon success. The possible values in the case of errors include 'unknown_error', 'user_cancelled', 'manifest_error', 'icon_error', 'invalid_id', 'permission_denied', and 'invalid_icon_url'."
+                "description": "A string result code, which will be empty upon success. The possible values in the case of errors include 'unknown_error', 'user_cancelled', 'manifest_error', 'icon_error', 'invalid_id', 'permission_denied', 'invalid_icon_url', 'signin_failed', and 'already_installed'."

[asargent_no_longer_on_chrome, 2013/05/21 19:47:24]

Can we switch to use an enum here? (I think we didn't have enum support at the
time it was originally written, so a list in the doc string was the best we
could do)

[calamity, 2013/05/24 00:24:28]

Hmm. Doing this causes the webstore to crash on install... I'm not sure why.

[asargent_no_longer_on_chrome, 2013/05/28 21:35:33]

Maybe a schema validation assertion being hit? With the current version we use
an empty string to signal success, but perhaps that's not compatible with enums?
Anyhow, that's fine to leave out of this CL if you can't get it working. 

               }
             ]
           }