terminal: use a11y messages from messages.json for xterm.js

Bug: b/236205389
Change-Id: I8f2be161c3b1dea359306f6dae220d685e468ac4
Reviewed-on: https://chromium-review.googlesource.com/c/apps/libapps/+/3974149
Reviewed-by: Joel Hockey <joelhockey@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/terminal/js/terminal_emulator.js b/terminal/js/terminal_emulator.js
index fbdce6c..a84ff8c 100644
--- a/terminal/js/terminal_emulator.js
+++ b/terminal/js/terminal_emulator.js
@@ -382,6 +382,8 @@
   }
 }
 
+let xtermTerminalStringsLoaded = false;
+
 /**
  * A terminal class that 1) uses xterm.js and 2) behaves like a `hterm.Terminal`
  * so that it can be used in existing code.
@@ -496,6 +498,13 @@
       selectionForeground: 'black',
     };
     this.observePrefs_();
+    if (!xtermTerminalStringsLoaded) {
+      xtermTerminalStringsLoaded = true;
+      Terminal.strings.promptLabel =
+          hterm.messageManager.get('TERMINAL_INPUT_LABEL');
+      Terminal.strings.tooMuchOutput =
+          hterm.messageManager.get('TERMINAL_TOO_MUCH_OUTPUT_MESSAGE');
+    }
   }
 
   /** @override */