Remove obsolete fieldtrial related code.

BUG=308692

Review URL: https://codereview.chromium.org/513803005

Cr-Commit-Position: refs/heads/master@{#292517}

tools/metrics/histograms/extract_histograms.py

@@ -42,9 +42,9 @@ XML below will generate the following five histograms:
 <histogram_suffixes_list>
 
 <histogram_suffixes name="BrowserType">
-  <group name="Chrome"/>
-  <group name="IE"/>
-  <group name="Firefox"/>
+  <suffix name="Chrome"/>
+  <suffix name="IE"/>
+  <suffix name="Firefox"/>
   <affected-histogram name="HistogramEnum"/>
 </histogram_suffixes>
 
@@ -307,15 +307,9 @@ def _UpdateHistogramsWithSuffixes(tree, histograms):
   """
   have_errors = False
 
-  # TODO(yiyaoliu): Remove this part after fieldtrial is not used any more.
-  if tree.getElementsByTagName('histogram_suffixes'):
-    histogram_suffix_tag = 'histogram_suffixes'
-    suffix_tag = 'suffix'
-    with_tag = 'with-suffix'
-  else:
-    histogram_suffix_tag = 'fieldtrial'
-    suffix_tag = 'group'
-    with_tag = 'with-group'
+  histogram_suffix_tag = 'histogram_suffixes'
+  suffix_tag = 'suffix'
+  with_tag = 'with-suffix'
 
   # Verify order of histogram_suffixes fields first.
   last_name = None

tools/metrics/histograms/pretty_print.py

@@ -40,10 +40,6 @@ ALPHABETIZATION_RULES = {
       'histogram_suffixes', lambda n: n.attributes['name'].value.lower()),
   'histogram_suffixes': ('affected-histogram',
                          lambda n: n.attributes['name'].value.lower()),
-  # TODO(yiyaoliu): Remove fieldtrial related pieces when it is not used.
-  'fieldtrials': ('fieldtrial', lambda n: n.attributes['name'].value.lower()),
-  'fieldtrial': ('affected-histogram',
-                 lambda n: n.attributes['name'].value.lower()),
 }
 
 

tools/metrics/histograms/print_style.py

@@ -20,11 +20,7 @@ ATTRIBUTE_ORDER = {
   'int': ['value', 'label'],
   'histogram_suffixes': ['name', 'separator', 'ordering'],
   'suffix': ['name', 'label'],
-  # TODO(yiyaoliu): Remove fieldtrial related pieces when it is not used.
-  'fieldtrial': ['name', 'separator', 'ordering'],
-  'group': ['name', 'label'],
   'affected-histogram': ['name'],
-  'with-group': ['name'],
   'with-suffix': ['name'],
 }
 
@@ -33,8 +29,6 @@ TAGS_THAT_DONT_INDENT = [
   'histogram-configuration',
   'histograms',
   'histogram_suffixes_list',
-  # TODO(yiyaoliu): Remove fieldtrial related pieces when it is not used.
-  'fieldtrials',
   'enums'
 ]
 
@@ -43,14 +37,11 @@ TAGS_THAT_DONT_INDENT = [
 TAGS_THAT_HAVE_EXTRA_NEWLINE = {
   'histogram-configuration': (2, 1, 1),
   'histograms': (2, 1, 1),
-  # TODO(yiyaoliu): Remove fieldtrial related pieces when it is not used.
-  'fieldtrials': (2, 1, 1),
+  'histogram': (1, 1, 1),
   'histogram_suffixes_list': (2, 1, 1),
   'histogram_suffixes': (1, 1, 1),
   'enums': (2, 1, 1),
-  'histogram': (1, 1, 1),
   'enum': (1, 1, 1),
-  'fieldtrial': (1, 1, 1),
 }
 
 # Tags that we allow to be squished into a single line for brevity.