Create FieldTrialAllocator.Size histogram

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 c3c216919320dd17de0f93f7def17a4a5a90b7c3..78af7ba49bb23adace9302e8d3d2d482c40a34de 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -66021,6 +66021,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="UMA.FieldTrialAllocator.Size" units="bytes">
+  <owner>lawrencewu@chromium.org</owner>
+  <owner>bcwhite@chromium.org</owner>
+  <owner>asvitkine@chromium.org</owner>
+  <summary>
+    Size, before padding, of objects allocated from persistent memory in the
+    browser process for field trials. Updated on each subprocess launch.
+  </summary>
+</histogram>
+
 <histogram name="UMA.FieldTrialsEnabledBenchmarking" enum="BooleanUsage">
   <obsolete>
     Deprecated 2012. No longer tracked.
@@ -66310,27 +66320,6 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
-<histogram name="UMA.PersistentAllocator.FieldTrialAllocator.Allocs"
-    units="bytes">
-  <owner>lawrencewu@chromium.org</owner>
-  <owner>bcwhite@chromium.org</owner>
-  <owner>asvitkine@chromium.org</owner>
-  <summary>
-    Size, before padding, of objects allocated from persistent memory in the
-    browser process for field trials. This is updated with every allocation.
-  </summary>
-</histogram>
-
-<histogram name="UMA.PersistentAllocator.FieldTrialAllocator.UsedPct" units="%">
-  <owner>lawrencewu@chromium.org</owner>
-  <owner>bcwhite@chromium.org</owner>
-  <owner>asvitkine@chromium.org</owner>
-  <summary>
-    Percentage of persistent memory segment that has been allocated. This is
-    updated only once per reporting cycle.
-  </summary>
-</histogram>
-
 <histogram name="UMA.PersistentAllocator.GpuMetrics.Allocs" units="bytes">
   <owner>bcwhite@chromium.org</owner>
   <owner>asvitkine@chromium.org</owner>