[ermine] Set Meta+Esc keyboard shortcut for Overview

Bug: 50223
Test: All unittests pass
Change-Id: Ida03c17e5bc6c4a081ee97cf2509b01643e5d45e
Reviewed-on: https://fuchsia-review.googlesource.com/c/experiences/+/409101
Reviewed-by: Chase Latta <chaselatta@google.com>
Testability-Review: Chase Latta <chaselatta@google.com>
Commit-Queue: Sanjay Chouksey <sanjayc@google.com>
diff --git a/session_shells/ermine/shell/config/keyboard_shortcuts.json b/session_shells/ermine/shell/config/keyboard_shortcuts.json
index 84e2ba4..532204e 100644
--- a/session_shells/ermine/shell/config/keyboard_shortcuts.json
+++ b/session_shells/ermine/shell/config/keyboard_shortcuts.json
@@ -22,8 +22,9 @@
   ],
   "overview": [
     {
+      "char": "escape",
       "modifier": "meta",
-      "chord": "Meta",
+      "chord": "Meta + Escape",
       "description": "Toggle Overview"
     }
   ],