Reorder ExtractHistogramsFromDom function

We want to update histograms with tokens first before updating
histograms with suffixes. As we're migrating to the new patterned
histgorams, some based histograms will be generated from variants so
_UpdateHistogramsWithTokens function need to be aware of that.

Bug: 758782
Change-Id: I94910b384d8880b9ed314a8b70dbe831c58a9de6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2464431Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Steven Holte <holte@chromium.org>
Auto-Submit: Weilun Shi <sweilun@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816844}

tools/metrics/histograms/extract_histograms.py

@@ -1004,9 +1004,9 @@ def ExtractHistogramsFromDom(tree):
   enums, enum_errors = ExtractEnumsFromXmlTree(enums_tree)
   histograms, histogram_errors = _ExtractHistogramsFromXmlTree(
       histograms_tree, enums)
+  histograms, update_token_errors = _UpdateHistogramsWithTokens(histograms)
   update_suffix_errors = _UpdateHistogramsWithSuffixes(histogram_suffixes_tree,
                                                        histograms)
-  histograms, update_token_errors = _UpdateHistogramsWithTokens(histograms)
 
   return histograms, (enum_errors or histogram_errors or update_suffix_errors
                       or update_token_errors)