Added histograms for newly added use counters.

Following https://codereview.chromium.org/649183007/ , I've updated the
histograms file on the Chrome side.

Review URL: https://codereview.chromium.org/663393002

Cr-Commit-Position: refs/heads/master@{#300638}

tools/metrics/histograms/histograms.xml

@@ -43991,6 +43991,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="568" label="SVGPathSegDOM"/>
   <int value="569" label="SVGTransformListConsolidate"/>
   <int value="570" label="SVGAnimatedTransformListBaseVal"/>
+  <int value="571" label="QuotedAnimationName"/>
+  <int value="572" label="QuotedKeyframesRule"/>
+  <int value="573" label="SrcsetDroppedCandidate"/>
 </enum>
 
 <enum name="FFmpegCodecs" type="int">