Update histograms.xml for recent Blink UseCounter addition.

tools/metrics/histograms/histograms.xml

 <!--
 Copyright 2013 The Chromium Authors. All rights reserved.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 
 <!--
 This file is used to generate a comprehensive list of Chrome histograms along
 with a detailed description for each histogram.
 
@@ skipping 16915 matching lines @@
   <int value="44" label="PatternAttribute"/>
   <int value="45" label="PlaceholderAttribute"/>
   <int value="46" label="PrecisionAttribute"/>
   <int value="47" label="PrefixedDirectoryAttribute"/>
   <int value="48" label="PrefixedSpeechAttribute"/>
   <int value="49" label="RequiredAttribute"/>
   <int value="50" label="ResultsAttribute"/>
   <int value="51" label="StepAttribute"/>
   <int value="52" label="PageVisits"/>
   <int value="53" label="HTMLMarqueeElement"/>
-  <int value="54" label="CSSOverflowMarquee"/>
+  <int value="54" label="Unused: CSSOverflowMarquee"/>
   <int value="55" label="Reflection"/>
   <int value="56" label="CursorVisibility"/>
   <int value="57" label="StorageInfo"/>
   <int value="58" label="XFrameOptions"/>
   <int value="59" label="XFrameOptionsSameOrigin"/>
   <int value="60" label="XFrameOptionsSameOriginWithBadAncestorChain"/>
   <int value="61" label="DeprecatedFlexboxWebContent"/>
   <int value="62" label="DeprecatedFlexboxChrome"/>
   <int value="63" label="DeprecatedFlexboxChromeExtension"/>
   <int value="64" label="SVGTRefElement"/>
   <int value="65" label="UnprefixedPerformanceTimeline"/>
   <int value="66" label="PrefixedPerformanceTimeline"/>
   <int value="67" label="UnprefixedUserTiming"/>
   <int value="68" label="PrefixedUserTiming"/>
   <int value="69" label="WindowEvent"/>
   <int value="70" label="ContentSecurityPolicyWithBaseElement"/>
   <int value="71" label="PrefixedMediaAddKey"/>
   <int value="72" label="PrefixedMediaGenerateKeyRequest"/>
   <int value="73" label="WebAudioLooping"/>
   <int value="74" label="DocumentClear"/>
   <int value="75" label="PrefixedTransitionMediaFeature"/>
   <int value="76" label="SVGFontElement"/>
   <int value="77" label="XMLDocument"/>
   <int value="78" label="XSLProcessingInstruction"/>
   <int value="79" label="XSLTProcessor"/>
+  <int value="80" label="SVGSwitchElement"/>
+  <int value="81" label="PrefixedDocumentRegister"/>
+  <int value="82" label="HTMLShadowElementOlderShadowRoot"/>
+  <int value="83" label="Document.all()"/>
+  <int value="84" label="FormElement"/>
+  <int value="85" label="DemotedFormElement"/>
+  <int value="86" label="CaptureAttributeAsEnum"/>
+  <int value="87" label="ShadowDOMPrefixedPseudo"/>
+  <int value="88" label="ShadowDOMPrefixedCreateShadowRoot"/>
+  <int value="89" label="ShadowDOMPrefixedShadowRoot"/>
+  <int value="90" label="SVGAnimationElement"/>
 </enum>
 
 <enum name="FFmpegCodecs" type="int">
   <int value="0" label="NONE"/>
   <int value="1" label="MPEG1VIDEO"/>
   <int value="2" label="MPEG2VIDEO"/>
   <int value="3" label="MPEG2VIDEO_XVMC"/>
   <int value="4" label="H261"/>
   <int value="5" label="H263"/>
   <int value="6" label="RV10"/>
@@ skipping 6593 matching lines @@
   <group name="Disabled" label="Neither extra webstore link is visible"/>
   <group name="FooterLink" label="Link in bottom right of footer"/>
   <group name="PlusIcon" label="Plus icon in apps page"/>
   <affected-histogram name="Extensions.AppLaunch"/>
   <affected-histogram name="NewTabPage.DefaultPageType"/>
 </fieldtrial>
 
 </fieldtrials>
 
 </histogram-configuration>