Clean up histograms.xml formatting

tools/metrics/histograms/extract_histograms.py

Index: tools/metrics/histograms/extract_histograms.py
diff --git a/tools/metrics/histograms/extract_histograms.py b/tools/metrics/histograms/extract_histograms.py
index c36334a7ee8ae765a82d23a6c8fa33ab0deda10f..6932bea3df48bb72658d6b2e7d1d1c496dacdd79 100644
--- a/tools/metrics/histograms/extract_histograms.py
+++ b/tools/metrics/histograms/extract_histograms.py
@@ -39,16 +39,16 @@ XML below will generate the following five histograms:
 
 </enums>
 
-<histogram_suffixes_list>
+<histogram-suffixes-list>
 
-<histogram_suffixes name="BrowserType">
+<histogram-suffixes name="BrowserType">
   <suffix name="Chrome"/>
   <suffix name="IE"/>
   <suffix name="Firefox"/>
   <affected-histogram name="HistogramEnum"/>
-</histogram_suffixes>
+</histogram-suffixes>
 
-</histogram_suffixes_list>
+</histogram-suffixes-list>
 
 </histogram-configuration>
 
@@ -184,11 +184,6 @@ def _ExtractEnumsFromXmlTree(tree):
 
   last_name = None
   for enum in tree.getElementsByTagName('enum'):
-    if enum.getAttribute('type') != 'int':
-      logging.error('Unknown enum type %s', enum.getAttribute('type'))
-      have_errors = True
-      continue
-
     name = enum.getAttribute('name')
     if last_name is not None and name.lower() < last_name.lower():
       logging.error('Enums %s and %s are not in alphabetical order',