GRIT: Enable variable expansion in filenames during HTML inlining.

grit/gather/chrome_html.py

Index: grit/gather/chrome_html.py
diff --git a/grit/gather/chrome_html.py b/grit/gather/chrome_html.py
index d5a2b07cd0e61bc44819bf23ac95c7abc1692601..a1c1f79aa6a42dad4ff0af713b0a626e193ab440 100644
--- a/grit/gather/chrome_html.py
+++ b/grit/gather/chrome_html.py
@@ -238,6 +238,7 @@ class ChromeHtml(interface.GathererBase):
     # 1x resources are implicitly already in the source and do not need to be
     # added.
     self.scale_factors_ = []
+    self.filename_expansion_function = None
 
   def SetAttributes(self, attrs):
     self.allow_external_script_ = ('allowexternalscript' in attrs and
@@ -267,7 +268,8 @@ class ChromeHtml(interface.GathererBase):
           self.grd_node.ToRealPath(self.GetInputPath()),
           allow_external_script=self.allow_external_script_,
           rewrite_function=lambda fp, t, d: ProcessImageSets(
-              fp, t, self.scale_factors_, d))
+              fp, t, self.scale_factors_, d),
+          filename_expansion_function=self.filename_expansion_function)
     return []
 
   def Translate(self, lang, pseudo_if_not_available=True,
@@ -275,10 +277,15 @@ class ChromeHtml(interface.GathererBase):
     """Returns this document translated."""
     return self.inlined_text_
 
+  def SetFilenameExpansionFunction(self, fn):
+    self.filename_expansion_function = fn
+
   def Parse(self):
     """Parses and inlines the represented file."""
 
     filename = self.GetInputPath()
+    if self.filename_expansion_function:
+      filename = self.filename_expansion_function(filename)
     # Hack: some unit tests supply an absolute path and no root node.
     if not os.path.isabs(filename):
       filename = self.grd_node.ToRealPath(filename)
@@ -288,7 +295,8 @@ class ChromeHtml(interface.GathererBase):
           self.grd_node,
           allow_external_script = self.allow_external_script_,
           rewrite_function=lambda fp, t, d: ProcessImageSets(
-              fp, t, self.scale_factors_, d))
+              fp, t, self.scale_factors_, d),
+          filename_expansion_function=self.filename_expansion_function)
     else:
       distribution = html_inline.GetDistribution()
       self.inlined_text_ = ProcessImageSets(