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 b09b06a4ddb59ad615874c4d685a5875bee3066c..d1c252caa3dc69dd782ffd6ab5952fba80b5069a 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...
+      </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...