Obsolete the Google Now Histograms

Google Now has been removed from the build for quite some time.

Fixed: 1088810
Change-Id: Id156fd6745a5ba13f404c7848b8ba1271b8ba049
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2231879
Auto-Submit: Robert Liao <robliao@chromium.org>
Commit-Queue: Steven Holte <holte@chromium.org>
Reviewed-by: Travis Skare <skare@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#775767}

tools/metrics/histograms/histograms.xml

@@ -62311,6 +62311,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="GoogleNow.Card.Button.Clicked0" enum="GoogleNowCardTypeId"
     expires_after="M85">
+  <obsolete>
+    Removed in r454917 03/2017.
+  </obsolete>
   <owner>robliao@chromium.org</owner>
   <owner>skare@chromium.org</owner>
   <summary>Types of cards which received an index 0 button click.</summary>
@@ -62318,6 +62321,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="GoogleNow.Card.Button.Clicked1" enum="GoogleNowCardTypeId"
     expires_after="M85">
+  <obsolete>
+    Removed in r454917 03/2017.
+  </obsolete>
   <owner>robliao@chromium.org</owner>
   <owner>skare@chromium.org</owner>
   <summary>Types of cards which received an index 1 button click.</summary>
@@ -62325,12 +62331,18 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="GoogleNow.Card.Clicked" enum="GoogleNowCardTypeId"
     expires_after="M85">
+  <obsolete>
+    Removed in r454917 03/2017.
+  </obsolete>
   <owner>robliao@chromium.org</owner>
   <owner>skare@chromium.org</owner>
   <summary>Types of cards which received a notification click.</summary>
 </histogram>
 
 <histogram name="GoogleNow.Event" enum="GoogleNowEvent" expires_after="M85">
+  <obsolete>
+    Removed in r454917 03/2017.
+  </obsolete>
   <owner>robliao@chromium.org</owner>
   <owner>skare@chromium.org</owner>
   <summary>Events in Google Now component extension.</summary>
@@ -62338,6 +62350,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="GoogleNow.MessageCenter.Displayed.NotificationsVisible"
     units="count" expires_after="M85">
+  <obsolete>
+    Removed in r455117 03/2017.
+  </obsolete>
   <owner>robliao@chromium.org</owner>
   <owner>skare@chromium.org</owner>
   <summary>