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 $TARGET_DIR
+mkdir -p "$TARGET_DIR"

[Sergey Ulanov, 2015/01/06 17:29:59]

Some of these changes were already landed in
https://codereview.chromium.org/569083002. I'm assuming you just haven't synced.

 
 # 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
+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
+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."