Update histograms.xml for recent Blink UseCounter addition.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 2e86f1d088289f262a36ef1e474cb41a787c460a..c86e0343cce0381721b3a09198b5cbbe6dd859f2 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -16892,7 +16892,7 @@ other types of suffix sets.
   <int value="19" label="UnprefixedTransitionEndEvent"/>
   <int value="20" label="PrefixedAndUnprefixedTransitionEndEvent"/>
   <int value="21" label="AutoFocusAttribute"/>
-  <int value="22" label="DeprecatedAutoSaveAttribute"/>
+  <int value="22" label="SVGAnimationElement"/>

[Ilya Sherman, 2013/07/26 01:20:30]

Hmm, why did this enum value change?  Was it wrong before?  If not, this change
will make it hard to make sense of data on the dashboard, as there will be
conflicting meanings for this enum value depending on the version of Chrome
that's uploading the data :(

[tkent, 2013/07/26 01:38:41]

Hmm, counting SVGAnimationElement started on July 11.  Only Canary and Dev have
it. We can change the enum value.

   <int value="23" label="DataListElement"/>
   <int value="24" label="FormAttribute"/>
   <int value="25" label="IncrementalAttribute"/>
@@ -16924,7 +16924,7 @@ other types of suffix sets.
   <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"/>
@@ -16950,6 +16950,16 @@ other types of suffix sets.
   <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"/>
 </enum>
 
 <enum name="FFmpegCodecs" type="int">