Remove histograms NewTabPage.IconsReal/IconsColor/IconsGray

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 a411ad83ecea1149225dd8ab548962fce38a0ed4..e3eb69a57bfe340daf0378d74d97fb37d5a4d595 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -41298,6 +41298,10 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="NewTabPage.IconsColor">
+  <obsolete>
+    Deprecated 2017-04, replaced by NewTabPage.TileType and
+    NewTabPage.SuggestionsImpression.IconsColor.
+  </obsolete>
   <owner>newt@chromium.org</owner>
   <summary>
     The number of most visited tiles on the new tab page that are displayed
@@ -41307,6 +41311,10 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="NewTabPage.IconsGray">
+  <obsolete>
+    Deprecated 2017-04, replaced by NewTabPage.TileType and
+    NewTabPage.SuggestionsImpression.IconsGray.
+  </obsolete>
   <owner>newt@chromium.org</owner>
   <summary>
     The number of most visited tiles on the new tab page that are displayed as
@@ -41315,6 +41323,10 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="NewTabPage.IconsReal">
+  <obsolete>
+    Deprecated 2017-04, replaced by NewTabPage.TileType and
+    NewTabPage.SuggestionsImpression.IconsReal.
+  </obsolete>
   <owner>newt@chromium.org</owner>
   <summary>
     The number of most visited tiles on the new tab page that are displayed with