[Files.app] Fix the tabindex around search box

ui/file_manager/file_manager/foreground/js/ui/search_box.js

Index: ui/file_manager/file_manager/foreground/js/ui/search_box.js
diff --git a/ui/file_manager/file_manager/foreground/js/ui/search_box.js b/ui/file_manager/file_manager/foreground/js/ui/search_box.js
index 3ed4f992322c20554a7ffce9395d7b911fc775d5..6392a6361333e9f449dce7ac83bf101b130de1e4 100644
--- a/ui/file_manager/file_manager/foreground/js/ui/search_box.js
+++ b/ui/file_manager/file_manager/foreground/js/ui/search_box.js
@@ -194,8 +194,8 @@ SearchBox.prototype.onInput_ = function() {
  */
 SearchBox.prototype.onFocus_ = function() {
   this.element.classList.toggle('has-cursor', true);
-  this.inputElement.tabIndex = '99';  // See: go/filesapp-tabindex.
   this.autocompleteList.attachToInput(this.inputElement);
+  this.updateStyles_();
 };
 
 /**
@@ -204,8 +204,8 @@ SearchBox.prototype.onFocus_ = function() {
  */
 SearchBox.prototype.onBlur_ = function() {
   this.element.classList.toggle('has-cursor', false);
-  this.inputElement.tabIndex = '-1';
   this.autocompleteList.detach();
+  this.updateStyles_();
 };
 
 /**
@@ -216,8 +216,10 @@ SearchBox.prototype.onBlur_ = function() {
 SearchBox.prototype.onKeyDown_ = function(event) {
   event = /** @type {KeyboardEvent} */ (event);
   // Handle only Esc key now.
-  if (event.keyCode != 27 || this.inputElement.value)
+  if (event.keyIdentifier != 'U+001B' /* Esc */ || this.inputElement.value)
     return;
+
+  this.inputElement.tabIndex = '-1';  // Focus to default element after blur.
   this.inputElement.blur();
 };
 
@@ -248,8 +250,13 @@ SearchBox.prototype.onDragEnd_ = function() {
  * @private
  */
 SearchBox.prototype.updateStyles_ = function() {
-  this.element.classList.toggle('has-text',
-                                !!this.inputElement.value);
+  var hasText = !!this.inputElement.value;
+  this.element.classList.toggle('has-text', hasText);
+  var hasFocusOnInput = this.element.classList.contains('has-cursor');
+
+  // See go/filesapp-tabindex for tabindexes.
+  this.inputElement.tabIndex = (hasText || hasFocusOnInput) ? '13' : '-1';
+  this.searchButton.tabIndex = (hasText || hasFocusOnInput) ? '-1' : '12';
 };
 
 /**