Fix string escaping in (un)install scripts of native messaging example

chrome/common/extensions/docs/examples/api/nativeMessaging/host/install_host.sh

 #!/bin/sh
 # Copyright 2013 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.
 
 set -e
 
 DIR="$( cd "$( dirname "$0" )" && pwd )"
-if [ $(uname -s) == 'Darwin' ]; then
+if [ "$(uname -s)" == "Darwin" ]; then
   if [ "$(whoami)" == "root" ]; then
     TARGET_DIR="/Library/Google/Chrome/NativeMessagingHosts"
   else
-    TARGET_DIR="
-        $HOME/Library/Application Support/Google/Chrome/NativeMessagingHosts"
+    TARGET_DIR="$HOME/Library/Application Support/Google/Chrome/NativeMessagingHosts"
   fi
 else
   if [ "$(whoami)" == "root" ]; then
     TARGET_DIR="/etc/opt/chrome/native-messaging-hosts"
   else
     TARGET_DIR="$HOME/.config/google-chrome/NativeMessagingHosts"
   fi
 fi
 
 HOST_NAME=com.google.chrome.example.echo
 
 # Create directory to store native messaging host.
 mkdir -p "$TARGET_DIR"
 
 # Copy native messaging host manifest.
-cp $DIR/$HOST_NAME.json "$TARGET_DIR"
+cp "$DIR/$HOST_NAME.json" "$TARGET_DIR"
 
 # Update host path in the manifest.
 HOST_PATH=$DIR/native-messaging-example-host
 ESCAPED_HOST_PATH=${HOST_PATH////\\/}
 sed -i -e "s/HOST_PATH/$ESCAPED_HOST_PATH/" "$TARGET_DIR/$HOST_NAME.json"
 
 # Set permissions for the manifest so that all users can read it.
 chmod o+r "$TARGET_DIR/$HOST_NAME.json"
 
-echo Native messaging host $HOST_NAME has been installed.
+echo "Native messaging host $HOST_NAME has been installed."