Small optimization to find_unused_resources.py.

tools/resources/find_unused_resources.py

 #!/usr/bin/env python
 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """This script searches for unused art assets listed in a .grd file.
 
 It uses git grep to look for references to the IDR resource id or the base
 filename. If neither is found, the file is reported unused.
 
@@ skipping 80 matching lines @@
   # Match the resource id and file path out of substrings like:
   # ...name="IDR_FOO_123" file="common/foo.png"...
   # by matching between the quotation marks.
   pattern = re.compile(
       r"""name="([^"]*)"  # Match resource ID between quotes.
       \s*                 # Run of whitespace, including newlines.
       file="([^"]*)"      # Match file path between quotes.""",
       re.VERBOSE)
   # Use finditer over the file contents because there may be newlines between
   # the name and file attributes.
+  searched = set()
   for result in pattern.finditer(grd_data):
     # Extract the IDR resource id and file path.
     resource_id = result.group(1)
     filepath = result.group(2)
     filename = os.path.basename(filepath)
+    base_resource_id = GetBaseResourceId(resource_id)
+
+    # Do not bother repeating searches.
+    key = (base_resource_id, filename)
+    if key in searched:
+      continue
+    searched.add(key)
+
     # Print progress as we go along.
     print resource_id
+
     # Ensure the resource isn't used anywhere by checking both for the resource
     # id (which should appear in C++ code) and the raw filename (in case the
     # file is referenced in a script, test HTML file, etc.).
-    base_resource_id = GetBaseResourceId(resource_id)
     matching_files = FindFilesWithContents(base_resource_id, filename)
+
     # Each file is matched once in the resource file itself. If there are no
     # other matching files, it is unused.
     if len(matching_files) == 1:
       # Give the user some happy news.
       print 'Unused!'
       unused_resources.append([resource_id, filepath])
 
   return unused_resources
 
 
@@ skipping 62 matching lines @@
   # Print a list of 'git rm' command lines to remove unused assets.
   print
   print 'Unused files:'
   for resource_id, filepath in unused_resources:
     for directory in scale_directories:
       print 'git rm ' + os.path.join(directory, filepath)
 
 
 if __name__ == '__main__':
   main()