In case of search add "Searching..." string to the spinner in the center.

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 4fbb7815199335249065bf3f2fc65c280f210935..fbe61f1cbb6aa4e73380ff34f2cae9a796cbfba6 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -11506,6 +11506,9 @@ Some features may be unavailable.  Please check that the profile exists and you
       <message name="IDS_FILE_BROWSER_SEARCH_EXPAND" desc="In the File Manager, the text on the link to expand search when no matching files were found.">
         Search all <ph name="DRIVE_NAME">$1<ex>Downloads</ex></ph>
       </message>
+      <message name="IDS_FILE_BROWSER_SEARCHING_SPINNER" desc="In the File Manager, the text is shown near the spinner while waiting for the results of a search.">
+        Searching...

[cpu_(ooo_6.6-7.5), 2012/07/30 21:25:29]

suggestion
IDS_FILE_BROWSER_SEARCHING_SPINNER --> IDS_FILE_BROWSER_SEARCH_SPINNER

+      </message
 
       <message name="IDS_FILE_BROWSER_CHANGE_DEFAULT_MENU_ITEM" desc="In the File Manager, the text in the menu item to change the default action for a particular file type.">
         Change default...