Add onfocuschange to the Extended Search API, with associated isFocused attribute.

chrome/common/omnibox_focus_state.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_COMMON_OMNIBOX_FOCUS_STATE_H_
 #define CHROME_COMMON_OMNIBOX_FOCUS_STATE_H_
 
 // Omnibox focus state.
 enum OmniboxFocusState {
   // Not focused.
   OMNIBOX_FOCUS_NONE,
 
   // Visibly focused.
   OMNIBOX_FOCUS_VISIBLE,
 
   // Invisibly focused, i.e. focused with a hidden caret.
   //
   // Omnibox will not look focused visibly but any user key strokes will go to
   // the omnibox.
   OMNIBOX_FOCUS_INVISIBLE,
 };
 
+// Reasons why the Omnibox focus state could change.
+enum OmniboxFocusChangeReason {
+  // Includes any explicit changes to focus. (e.g. user clicking to change
+  // focus, user tabbing to change focus, any explicit calls to SetFocus,
+  // etc.)
+  OMNIBOX_FOCUS_CHANGE_EXPLICIT,
+
+  // Focus changed to restore state from a tab the user switched to.
+  OMNIBOX_FOCUS_CHANGE_TAB_SWITCH,
+
+  // Focus changed because user started typing. This only happens when focus
+  // state is INVISIBLE (and this results in a change to VISIBLE).
+  OMNIBOX_FOCUS_CHANGE_TYPING,
+};
+
 #endif  // CHROME_COMMON_OMNIBOX_FOCUS_STATE_H_