Make image set insertion work in more cases

grit/gather/chrome_html.py

Index: grit/gather/chrome_html.py
===================================================================
--- grit/gather/chrome_html.py	(revision 134)
+++ grit/gather/chrome_html.py	(working copy)
@@ -31,18 +31,22 @@
 # Matches a chrome theme source URL.
 _THEME_SOURCE = lazy_re.compile(
     '(?P<baseurl>chrome://theme/IDR_[A-Z0-9_]*)(?P<query>\?.*)?')
-# Matches CSS image urls with the capture group 'filename'.
+# Pattern for matching CSS url() function.
+_CSS_URL_PATTERN = 'url\((?P<quote>"|\'|)(?P<filename>[^"\'()]*)(?P=quote)\)'
+# Matches CSS url() functions with the capture group 'filename'.
+_CSS_URL = lazy_re.compile(_CSS_URL_PATTERN)
+# Matches one or more CSS image urls used in given properties.
 _CSS_IMAGE_URLS = lazy_re.compile(
-    '(?P<attribute>content|background|[\w-]*-image):[ ]*' +
-    'url\((?P<quote>"|\'|)(?P<filename>[^"\'()]*)(?P=quote)')
+    '(?P<attribute>content|background|[\w-]*-image):\s*' +
+        '(?P<urls>(' + _CSS_URL_PATTERN + '\s*,?\s*)+)')
 # Matches CSS image sets.
 _CSS_IMAGE_SETS = lazy_re.compile(
     '(?P<attribute>content|background|[\w-]*-image):[ ]*' +
         '-webkit-image-set\((?P<images>' +
-        '([,\r\n ]*url\((?P<quote>"|\'|)[^"\'()]*(?P=quote)\)[ ]*[0-9.]*x)*)\)',
+        '(\s*,?\s*url\((?P<quote>"|\'|)[^"\'()]*(?P=quote)\)[ ]*[0-9.]*x)*)\)',
     re.MULTILINE)
 # Matches a single image in a CSS image set with the capture group scale.
-_CSS_IMAGE_SET_IMAGE = lazy_re.compile('[,\r\n ]*' +
+_CSS_IMAGE_SET_IMAGE = lazy_re.compile('\s*,?\s*' +
     'url\((?P<quote>"|\'|)[^"\'()]*(?P=quote)\)[ ]*(?P<scale>[0-9.]*x)',
     re.MULTILINE)
 _HTML_IMAGE_SRC = lazy_re.compile(
@@ -121,10 +125,10 @@
   return "-webkit-image-set(%s)" % (', '.join(imageset))
 
 
-def InsertImageSet(
+def UrlToImageSet(
     src_match, base_path, scale_factors, distribution,
     filename_expansion_function=None):
-  """Regex replace function which inserts -webkit-image-set.
+  """Regex replace function which replaces url() with -webkit-image-set.
 
   Takes a regex match for url('path'). If the file is local, checks for
   files of the same name in folders corresponding to the supported scale
@@ -134,7 +138,7 @@
   scale factor.
 
   Args:
-    src_match: regex match object from _CSS_IMAGE_URLS
+    src_match: regex match object from _CSS_URLS
     base_path: path to look for relative file paths in
     scale_factors: a list of the supported scale factors (i.e. ['2x'])
     distribution: string that should replace %DISTRIBUTION%.
@@ -144,7 +148,6 @@
   """
   quote = src_match.group('quote')
   filename = src_match.group('filename')
-  attr = src_match.group('attribute')
   image_list = GetImageList(
       base_path, filename, scale_factors, distribution,
       filename_expansion_function=filename_expansion_function)
@@ -153,9 +156,35 @@
   if len(image_list) == 1:
     return src_match.group(0)
 
-  return "%s: %s" % (attr, GenerateImageSet(image_list, quote)[:-1])
+  return GenerateImageSet(image_list, quote)
 
 
+def InsertImageSet(
+    src_match, base_path, scale_factors, distribution,
+    filename_expansion_function=None):
+  """Regex replace function which inserts -webkit-image-set rules.
+
+  Takes a regex match for `property: url('path')[, url('path')]+`.
+  Replaces one or more occurances of the match with image set rules.
+
+  Args:
+    src_match: regex match object from _CSS_IMAGE_URLS
+    base_path: path to look for relative file paths in
+    scale_factors: a list of the supported scale factors (i.e. ['2x'])
+    distribution: string that should replace %DISTRIBUTION%.
+
+  Returns:
+    string
+  """
+  attr = src_match.group('attribute')
+  urls = _CSS_URL.sub(
+      lambda m: UrlToImageSet(m, base_path, scale_factors, distribution,
+                              filename_expansion_function),
+      src_match.group('urls'))
+
+  return "%s: %s" % (attr, urls)
+
+
 def InsertImageStyle(
     src_match, base_path, scale_factors, distribution,
     filename_expansion_function=None):