143570 r=bzbarsky sr=darin

Allow assigning helper apps to mailnews attachments by extension.

do this by only getting the query off the uri for HTTP/HTTPS urls - mailnews
uris always have a query string, and if there is a query string the file
extension is ignored because a CGI script is assumed, which has no useful
extension.

uriloader/exthandler/nsExternalHelperAppService.cpp

@@ -364,6 +364,7 @@ NS_IMETHODIMP nsExternalHelperAppService::DoContent(const char *aMimeContentType
                                                     nsIStreamListener ** aStreamListener)
 {
   nsCAutoString fileExtension;
+  nsresult rv;
 
   // Get the file extension that we will need later
   nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
@@ -397,7 +398,6 @@ NS_IMETHODIMP nsExternalHelperAppService::DoContent(const char *aMimeContentType
       }
     }
 
-
     // If the method is post, don't bother getting the file extension;
     // it will belong to a CGI script anyway
     // Also, if we already have an extension, don't bother
@@ -406,7 +406,19 @@ NS_IMETHODIMP nsExternalHelperAppService::DoContent(const char *aMimeContentType
 
       if (url) {
         nsCAutoString query;
+
+        // We only care about the query for HTTP and HTTPS URLs
+        PRBool isHTTP, isHTTPS;
+        rv = uri->SchemeIs("http", &isHTTP);
+        if (NS_FAILED(rv))
+          isHTTP = PR_FALSE;
+        rv = uri->SchemeIs("https", &isHTTPS);
+        if (NS_FAILED(rv))
+          isHTTPS = PR_FALSE;
+
+        if (isHTTP || isHTTPS)
           url->GetQuery(query);
+
         // Only get the extension if the query is empty; if it isn't, then the
         // extension likely belongs to a cgi script and isn't helpful
         if (query.IsEmpty())
@@ -427,7 +439,6 @@ NS_IMETHODIMP nsExternalHelperAppService::DoContent(const char *aMimeContentType
   // and create a new mime info object for it and use it
   if (!mimeInfo)
   {
-    nsresult rv;
     mimeInfo = do_CreateInstance(NS_MIMEINFO_CONTRACTID, &rv);
     // If we still have no mime info, give up.
     if (NS_FAILED(rv))