[iOS][Default Promo][Metrics] Add action histogram for quick analysis

Adds 3 histograms:
IOS.DefaultBrowserFullscreenTailoredPromoAllTabs
IOS.DefaultBrowserFullscreenTailoredPromoMadeForIOS
IOS.DefaultBrowserFullscreenTailoredPromoStaySafe
To easily compare CTR on each tailored promo

Bug: 1205221
Change-Id: Iec93e12c9d64f16f597b9c752f9bad43ec72041c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2873115
Commit-Queue: Javier Flores <javierrobles@chromium.org>
Reviewed-by: Ali Juma <ajuma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#879418}
NOKEYCHECK=True
GitOrigin-RevId: 594a19b27b592d47bb673323ff7173c75cc4d038
diff --git a/metrics/histograms/histograms_xml/ios/histograms.xml b/metrics/histograms/histograms_xml/ios/histograms.xml
index 8e24197..daf6356 100644
--- a/metrics/histograms/histograms_xml/ios/histograms.xml
+++ b/metrics/histograms/histograms_xml/ios/histograms.xml
@@ -301,6 +301,36 @@
   </summary>
 </histogram>
 
+<histogram name="IOS.DefaultBrowserFullscreenTailoredPromoAllTabs"
+    enum="IOSDefaultBrowserFullscreenPromoAction" expires_after="2022-02-01">
+  <owner>javierrobles@chromium.org</owner>
+  <owner>rkgibson@chromium.org</owner>
+  <summary>
+    The action taken by the user in response to the &quot;All tabs&quot; default
+    browser tailored promo.
+  </summary>
+</histogram>
+
+<histogram name="IOS.DefaultBrowserFullscreenTailoredPromoMadeForIOS"
+    enum="IOSDefaultBrowserFullscreenPromoAction" expires_after="2022-02-01">
+  <owner>javierrobles@chromium.org</owner>
+  <owner>rkgibson@chromium.org</owner>
+  <summary>
+    The action taken by the user in response to the &quot;Made for iOS&quot;
+    default browser tailored promo.
+  </summary>
+</histogram>
+
+<histogram name="IOS.DefaultBrowserFullscreenTailoredPromoStaySafe"
+    enum="IOSDefaultBrowserFullscreenPromoAction" expires_after="2022-02-01">
+  <owner>javierrobles@chromium.org</owner>
+  <owner>rkgibson@chromium.org</owner>
+  <summary>
+    The action taken by the user in response to the &quot;Stay Safe&quot;
+    default browser tailored promo.
+  </summary>
+</histogram>
+
 <histogram name="IOS.DefaultBrowserPromo.TailoredFullscreen.{Action}"
     enum="IOSDefaultBrowserTailoredPromoType" expires_after="2022-04-20">
   <owner>javierrobles@chromium.org</owner>