Create reproducible NOTICE collections

Sort the lists of notice files instead of relying on the filesystem
ordering returned by os.walk

Bug: 23972440
Change-Id: Id32be9ce8e540244ad9d67b6fc7883fc2963fe5c
diff --git a/tools/generate-notice-files.py b/tools/generate-notice-files.py
index 4571b70..5b13bf5 100755
--- a/tools/generate-notice-files.py
+++ b/tools/generate-notice-files.py
@@ -99,7 +99,7 @@
     # most browsers, but href's to table row ids do)
     id_table = {}
     id_count = 0
-    for value in file_hash.values():
+    for value in file_hash:
         for filename in value:
              id_table[filename] = id_count
         id_count += 1
@@ -116,7 +116,7 @@
     print >> output_file, "<ul>"
 
     # Flatten the list of lists into a single list of filenames
-    sorted_filenames = sorted(itertools.chain.from_iterable(file_hash.values()))
+    sorted_filenames = sorted(itertools.chain.from_iterable(file_hash))
 
     # Print out a nice table of contents
     for filename in sorted_filenames:
@@ -127,11 +127,11 @@
     print >> output_file, "</div><!-- table of contents -->"
     # Output the individual notice file lists
     print >>output_file, '<table cellpadding="0" cellspacing="0" border="0">'
-    for value in file_hash.values():
+    for value in file_hash:
         print >> output_file, '<tr id="id%d"><td class="same-license">' % id_table.get(value[0])
         print >> output_file, '<div class="label">Notices for file(s):</div>'
         print >> output_file, '<div class="file-list">'
-        for filename in sorted(value):
+        for filename in value:
             print >> output_file, "%s <br/>" % (SRC_DIR_STRIP_RE.sub(r"\1", filename))
         print >> output_file, "</div><!-- file-list -->"
         print >> output_file
@@ -154,10 +154,10 @@
     SRC_DIR_STRIP_RE = re.compile(input_dir + "(/.*).txt")
     output_file = open(output_filename, "wb")
     print >> output_file, file_title
-    for value in file_hash.values():
+    for value in file_hash:
       print >> output_file, "============================================================"
       print >> output_file, "Notices for file(s):"
-      for filename in sorted(value):
+      for filename in value:
         print >> output_file, SRC_DIR_STRIP_RE.sub(r"\1", filename)
       print >> output_file, "------------------------------------------------------------"
       print >> output_file, open(value[0]).read()
@@ -178,11 +178,12 @@
                 file_md5sum = md5sum(filename)
                 files_with_same_hash[file_md5sum].append(filename)
 
+    filesets = [sorted(files_with_same_hash[md5]) for md5 in sorted(files_with_same_hash.keys())]
 
     print "Combining NOTICE files into HTML"
-    combine_notice_files_html(files_with_same_hash, input_dir, html_output_file)
+    combine_notice_files_html(filesets, input_dir, html_output_file)
     print "Combining NOTICE files into text"
-    combine_notice_files_text(files_with_same_hash, input_dir, txt_output_file, file_title)
+    combine_notice_files_text(filesets, input_dir, txt_output_file, file_title)
 
 if __name__ == "__main__":
     main(args)