Add memory ablation experiment.

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 72a733f9ef2639e6d54442cc13a124880be7ca6f..20f53dbeb1e75a13937193135660a85e01d1b48e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -101294,6 +101294,7 @@ from previous Chrome versions.
   <int value="-48920737" label="enable-smooth-scrolling"/>
   <int value="-45532639" label="enable-default-media-session"/>
   <int value="-45074716" label="SystemDownloadManager:disabled"/>
+  <int value="-29847483" label="MemoryAblation:enabled"/>
   <int value="-23090520" label="disable-search-button-in-omnibox"/>
   <int value="-22544408" label="enable-video-player-chromecast-support"/>
   <int value="-16824589" label="ash-shelf-color"/>
@@ -101659,6 +101660,7 @@ from previous Chrome versions.
   <int value="1421620678" label="simple-clear-browsing-data-support-string"/>
   <int value="1441897340" label="AndroidSpellCheckerNonLowEnd:enabled"/>
   <int value="1442798825" label="enable-quic"/>
+  <int value="1442830837" label="MemoryAblation:disabled"/>
   <int value="1454363479" label="disable-storage-manager"/>
   <int value="1458583431" label="arc-use-auth-endpoint"/>
   <int value="1459529277" label="disable-text-input-focus-manager"/>