Drive: Add "Clear Local Cache" in the Gear menu to clear all local cache of Drive.

chrome/browser/resources/file_manager/css/file_manager.css

Index: chrome/browser/resources/file_manager/css/file_manager.css
diff --git a/chrome/browser/resources/file_manager/css/file_manager.css b/chrome/browser/resources/file_manager/css/file_manager.css
index 819f16aa77a8f8e03778df52002972daa7918396..fa8b02f5caec41b6099de70f306a62c7e59a28b8 100644
--- a/chrome/browser/resources/file_manager/css/file_manager.css
+++ b/chrome/browser/resources/file_manager/css/file_manager.css
@@ -1306,6 +1306,10 @@ body:not([type='saveas-file']):not([type='full-page'])
   display: none;
 }
 
+body:not([ctrl-pressing]) [visibleif='ctrl'] {
+  display: none;
+}
+
 #gdata-settings {
   background-image: url('../images/files/ui/settings.svg');
   background-position: 20px center;