Change the shortcut of toggling caps lock to Alt+Search.

chrome/browser/resources/chromeos/keyboard_overlay_data.js

 // Copyright (c) 2012 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.
 
 var keyboardOverlayData = {
   'inputMethodIdToOverlayId': {
     'm17n:ar:kbd': 'ar',
     'm17n:fa:isiri': 'ar',
     'm17n:hi:itrans': 'hi',
     'm17n:th:kesmanee': 'th',
@@ skipping 15829 matching lines @@
     'p<>CTRL': 'keyboardOverlayPrint',
     'power': 'keyboardOverlayLockScreenOrPowerOff',
     'q<>CTRL<>SHIFT': 'keyboardOverlaySignOut',
     'r<>CTRL': 'keyboardOverlayReloadCurrentPage',
     'r<>CTRL<>SHIFT': 'keyboardOverlayReloadIgnoringCache',
     'right<>ALT': 'keyboardOverlayGoForward',
     'right<>CTRL': 'keyboardOverlayNextWord',
     'right<>CTRL<>SHIFT': 'keyboardOverlaySelectWordAtATime',
     's<>ALT<>SHIFT': 'keyboardOverlayFocusStatusIcon',
     's<>CTRL': 'keyboardOverlaySave',
-    'search<>SHIFT': 'keyboardOverlayToggleCapsLock',
+    'search<>ALT': 'keyboardOverlayToggleCapsLock',
     'space<>CTRL': 'keyboardOverlaySelectPreviousInputMethod',
     'space<>SHIFT': 'keyboardOverlayScrollUpOnePage',
     'switch window<>CTRL': 'keyboardOverlayTakeScreenshot',
     'switch window<>CTRL<>SHIFT': 'keyboardOverlayScreenshotRegion',
     't<>ALT<>SHIFT': 'keyboardOverlayFocusToolbar',
     't<>CTRL': 'keyboardOverlayNewTab',
     't<>CTRL<>SHIFT': 'keyboardOverlayReopenLastClosedTab',
     'tab<>ALT': 'keyboardOverlayNextWindow',
     'tab<>ALT<>SHIFT': 'keyboardOverlayPreviousWindow',
     'tab<>CTRL': 'keyboardOverlayActivateNextTab',
     'tab<>CTRL<>SHIFT': 'keyboardOverlayActivatePreviousTab',
     'u<>CTRL': 'keyboardOverlayViewSource',
     'u<>CTRL<>SHIFT': 'keyboardOverlayInputUnicodeCharacters',
     'up<>ALT': 'keyboardOverlayPageUp',
     'up<>ALT<>CTRL': 'keyboardOverlayHome',
     'v<>CTRL': 'keyboardOverlayPaste',
     'v<>CTRL<>SHIFT': 'keyboardOverlayPasteAsPlainText',
     'w<>CTRL': 'keyboardOverlayCloseTab',
     'w<>CTRL<>SHIFT': 'keyboardOverlayCloseWindow',
     'x<>CTRL': 'keyboardOverlayCut',
     'z<>ALT<>CTRL': 'keyboardOverlayToggleAccessibilityFeatures',
     'z<>CTRL': 'keyboardOverlayUndo'
   }
 };