MD History: show and hide search spinner and icon the same way

ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html

Index: ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html
diff --git a/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html b/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html
index d3fad815a74221a48dfcf09c4a81a0ea23b741be..9f9af393deb104ff166756a158ea196b0692f911 100644
--- a/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html
+++ b/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html
@@ -31,7 +31,11 @@
 
       #icon {
         --paper-icon-button-ink-color: white;
-        transition: opacity 150ms;
+      }
+
+      #icon,
+      paper-spinner-lite {
+        transition: opacity 200ms;
       }
 
       #prompt {
@@ -42,11 +46,16 @@
         --paper-spinner-color: white;
         height: 20px;
         margin: 0 6px;
+        opacity: 0;
         padding: 6px;
         position: absolute;
         width: 20px;
       }
 
+      paper-spinner-lite[active] {
+        opacity: 1;
+      }
+
       paper-input-container {
         --paper-input-container-input-color: white;
         --paper-input-container-underline: {