Replace __MSG_some_name__ template within extension css/html files with local...

chrome/common/filter_policy.h

Index: chrome/common/filter_policy.h
===================================================================
--- chrome/common/filter_policy.h	(revision 38490)
+++ chrome/common/filter_policy.h	(working copy)
@@ -11,12 +11,17 @@
 // can decide to filter it.  The filtering is done in the renderer.  This class
 // enumerates the different policy that can be used for the filtering.  It is
 // passed along with resource response messages.
+// It can be used for content post-processing, like message replacement within
+// extension css files.
 class FilterPolicy {
  public:
   enum Type {
     // Pass all types of resources through unmodified.
     DONT_FILTER = 0,
 
+    // Post-process extension css files.
+    FILTER_EXTENSION_MESSAGES,
+
     // Block all types of resources, except images.  For images, modify them to
     // indicate that they have been filtered.
     // TODO(abarth): This is a misleading name for this enum value.  We should