Define shortcuts for toggling IME layouts.

Out of the box, we want Alt-Left to toggle Emojis, while Alt-Right
toggles the shifted symbols layout.

Bug: 23954008
Bug: 24369173

Change-Id: I93dd66fb469e5d0a831359ff3a786fe68e1d73ea
(cherry picked from commit 411841b374aa04e333ea5a438dfd539f49ec589a)
diff --git a/java/res/values/config.xml b/java/res/values/config.xml
index 40760f6..33bcb06 100644
--- a/java/res/values/config.xml
+++ b/java/res/values/config.xml
@@ -91,4 +91,22 @@
     <fraction name="config_emoji_keyboard_row_height">33%p</fraction>
     <fraction name="config_emoji_keyboard_key_letter_size">68%p</fraction>
     <integer name="config_emoji_keyboard_max_page_key_count">21</integer>
+
+    <!-- Key codes of hardware keys that can be used to toggle the Emoji layout.
+         Each array defines a comma-separated tuple containing:
+         1. Key code constant from android.view.KeyEvent
+         2. Meta mask (if any) from android.view.KeyEvent
+         Used in EmojiAltPhysicalKeyDetector and KeyboardSwitcher. -->
+    <string-array name="keyboard_switcher_emoji" translatable="false">
+        <item>57,16</item> <!-- KeyEvent.KEYCODE_ALT_LEFT , KeyEvent.META_ALT_LEFT_ON -->
+    </string-array>
+
+    <!-- Key codes of hardware keys that can be used to toggle the Symbols (Shifted) layout.
+         Each array defines a comma-separated tuple containing:
+         1. Key code constant from android.view.KeyEvent
+         2. Meta mask (if any) from android.view.KeyEvent
+         Used in EmojiAltPhysicalKeyDetector and KeyboardSwitcher. -->
+    <string-array name="keyboard_switcher_symbols_shifted" translatable="false">
+        <item>58,32</item> <!-- KeyEvent.KEYCODE_ALT_RIGHT , KeyEvent.META_ALT_RIGHT_ON -->
+    </string-array>
 </resources>