Prerender: Remove PerceivedPLT histograms

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 b9111bb3ddfc3f3016e3dcb3737f9482bcee38ae..5622150dc424f7c1c1c3d4cdea3f268d0c57dd9f 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -53304,6 +53304,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Prerender.PerceivedPLT" units="ms">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     Time from when a user navigates to a page to when it loads. Since the pages
@@ -53315,6 +53318,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Prerender.PerceivedPLTFirstAfterMiss" units="ms">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     Time from when a user navigates to a page to when it loads. Since the pages
@@ -53327,6 +53333,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Prerender.PerceivedPLTFirstAfterMissAnyOnly" units="ms">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     Time from when a user navigates to a page to when it loads. Since the pages
@@ -53341,6 +53350,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Prerender.PerceivedPLTFirstAfterMissBoth" units="ms">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     Time from when a user navigates to a page to when it loads. Since the pages
@@ -53355,6 +53367,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Prerender.PerceivedPLTFirstAfterMissNonOverlapping" units="ms">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     Time from when a user navigates to a page to when it loads. Since the pages
@@ -53369,6 +53384,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="Prerender.PerceivedPLTFirstAfterMissNonOverlappingOnly"
     units="ms">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     Time from when a user navigates to a page to when it loads. Since the pages
@@ -53383,6 +53401,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Prerender.PerceivedPLTMatched" units="ms">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     Time from when a user navigates to a page to when it loads. Since the pages
@@ -53414,6 +53435,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Prerender.PerceivedPLTWindowed" units="ms">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     Time from when a user navigates to a page to when it loads. Since the pages
@@ -53426,6 +53450,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Prerender.PerceivedPLTWindowNotMatched" units="ms">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     Time from when a user navigates to a page to when it loads. Since the pages
@@ -53503,6 +53530,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Prerender.PrerenderCountOf3Max">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     After launching a prerender, how many simultanious prerenders are recorded
@@ -53511,6 +53541,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Prerender.PrerenderNotSwappedInPLT" units="ms">
+  <obsolete>
+    Deprecated 2017-03.
+  </obsolete>
   <owner>pasko@chromium.org</owner>
   <summary>
     For prerenders that finish loading before they are ever swapped in, their