Use JSONEncoder to escape JSON strings.

grit/format/chrome_messages_json.py

Index: grit/format/chrome_messages_json.py
diff --git a/grit/format/chrome_messages_json.py b/grit/format/chrome_messages_json.py
index 560912288b1562e483c07cfbf1bd35e2af1f30c5..7b370d7fdca26ed966b45ad0a42c709715b8885b 100644
--- a/grit/format/chrome_messages_json.py
+++ b/grit/format/chrome_messages_json.py
@@ -6,6 +6,7 @@
 """Formats as a .json file that can be used to localize Google Chrome
 extensions."""
 
+from json import JSONEncoder
 import re
 import types
 
@@ -16,20 +17,19 @@ def Format(root, lang='en', output_dir='.'):
   """Format the messages as JSON."""
   yield '{\n'
 
+  encoder = JSONEncoder();
   format = ('  "%s": {\n'
-            '    "message": "%s"\n'
+            '    "message": %s\n'
             '  }')
   first = True
   for child in root.ActiveDescendants():
     if isinstance(child, message.MessageNode):
-      loc_message = child.Translate(lang)
-      loc_message = re.sub(r'\\', r'\\\\', loc_message)
-      loc_message = re.sub(r'"', r'\"', loc_message)
-
       id = child.attrs['name']
       if id.startswith('IDR_'):
         id = id[4:]
 
+      loc_message = encoder.encode(child.Translate(lang))
+
       if not first:
         yield ',\n'
       first = False