Change shortcut to Ctrl/Cmd+Shift+A

Bug: 1099917
Change-Id: I8668b0dadf87721aec2c0d1ef42ffa94f769ab28
Reviewed-on: https://chrome-internal-review.googlesource.com/c/chrome/browser/resources/tab_search/+/3271919Reviewed-by: Robert Liao <robliao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819598}

chrome/browser/resources/tab_search_merge/app.js

@@ -293,7 +293,7 @@ export class TabSearchAppElement extends PolymerElement {
    * @private
    */
   getKeyboardShortcut_() {
-    return (isMac ? 'Cmd' : 'Ctrl') + '+Shift+E';
+    return (isMac ? 'Cmd' : 'Ctrl') + '+Shift+A';
   }
 
   /**