Use ' instead of " when rewriting -webkit-image-set.

grit/gather/chrome_html.py

Index: grit/gather/chrome_html.py
===================================================================
--- grit/gather/chrome_html.py	(revision 57)
+++ grit/gather/chrome_html.py	(working copy)
@@ -73,9 +73,9 @@
   # Any matches for which a chrome URL handler will serve all scale factors
   # can simply request all scale factors.
   if _THEME_SOURCE.match(filename):
-    images = ["url(\"%s\") %s" % (filename, '1x')]
+    images = ["url('%s') %s" % (filename, '1x')]
     for sc in scale_factors:
-      images.append("url(\"%s@%s\") %s" % (filename, sc, sc))
+      images.append("url('%s@%s') %s" % (filename, sc, sc))
     return "%s: -webkit-image-set(%s" % (attr, ', '.join(images))
 
   if filename.find(':') != -1:
@@ -84,7 +84,7 @@
 
   filename = filename.replace(DIST_SUBSTR, distribution)
   filepath = os.path.join(base_path, filename)
-  images = ["url(\"%s\") %s" % (filename, '1x')]
+  images = ["url('%s') %s" % (filename, '1x')]
 
   for sc in scale_factors:
     # Check for existence of file and add to image set.
@@ -95,7 +95,7 @@
       scale_image_name = re.sub('(?P<path>(.*/)?)(?P<file>[^/]*)',
                                 '\\g<path>' + sc + '/\\g<file>',
                                 filename)
-      images.append("url(\"%s\") %s" % (scale_image_name, sc))
+      images.append("url('%s') %s" % (scale_image_name, sc))
   return "%s: -webkit-image-set(%s" % (attr, ', '.join(images))