Update update_histogram_enum.py and update_use_counter_feature_enum.py for Blink rename

tools/metrics/histograms/update_use_counter_feature_enum.py

Index: tools/metrics/histograms/update_use_counter_feature_enum.py
diff --git a/tools/metrics/histograms/update_use_counter_feature_enum.py b/tools/metrics/histograms/update_use_counter_feature_enum.py
index 45a369bc12b0b302b26d47eae3f118fde4e7431a..a0bf042d12faaf20113db52c21f792b80ddd03fe 100755
--- a/tools/metrics/histograms/update_use_counter_feature_enum.py
+++ b/tools/metrics/histograms/update_use_counter_feature_enum.py
@@ -35,15 +35,16 @@ if __name__ == '__main__':
   source_path = 'third_party/WebKit/Source/core/frame/UseCounter.h'
 
   START_MARKER = '^enum Feature : uint32_t {'
-  END_MARKER = '^NumberOfFeatures'
+  END_MARKER = '^kNumberOfFeatures'
 
   if options.dashboard:
     enum_dict, ignored = ReadHistogramValues(source_path, START_MARKER,
-        END_MARKER)
+        END_MARKER, strip_k_prefix=True)
     PrintEnumForDashboard(enum_dict)
   else:
     UpdateHistogramEnum(
         histogram_enum_name='FeatureObserver',
         source_enum_path=source_path,
         start_marker=START_MARKER,
-        end_marker=END_MARKER)
+        end_marker=END_MARKER,
+        strip_k_prefix=True)