Add UMA metrics for pop-up blocked page action on desktop

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 3cd7f59a44de101be2885cde8f49a93e794e5096..9a527e401ba9106d772b8d0850d097e140ad88b6 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -7572,6 +7572,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="ContentSettings.Popups" enum="ContentSettingPopupAction">
+  <owner>charleszhao@chromium.org</owner>
+  <summary>
+    Tracks whether the popup content blocked puzzle piece was shown in the
+    Omnibox, and how the user interacted with it.
+  </summary>
+</histogram>
+
 <histogram name="ContextMenu.SaveLinkType" enum="ContextMenuSaveLinkType">
   <owner>qinmin@chromium.org</owner>
   <summary>
@@ -80075,6 +80083,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="6" label="Clicked 'Learn more'"/>
 </enum>
 
+<enum name="ContentSettingPopupAction" type="int">
+  <int value="0" label="Displayed popup-blocked icon in Omnibox"/>
+  <int value="1" label="Displayed bubble"/>
+  <int value="2" label="Clicked 'Always allow pop-ups from'"/>
+  <int value="3" label="Clicked one of the list items"/>
+  <int value="4" label="Clicked 'Manage pop-up blocking'"/>
+</enum>
+
 <enum name="ContentSettingScheme" type="int">
   <int value="0" label="(wildcard)"/>
   <int value="1" label="(other)"/>