Implementing sign-in promo histograms for bookmark

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 b99d769b2489f47fde23e8c21ec037eeb70fbae8..d01ed711ee07533af90e80ce14d037c128baec39 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -32490,6 +32490,35 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="MobileSignInPromo.BookmarkManager.ImpressionsTilDismiss"
+    units="impressions">
+  <owner>jlebel@chromium.org</owner>
+  <summary>
+    Counts how many times the signin promo is implicitly dismissed (by closing
+    the bookmark manager) per impression.
+  </summary>
+</histogram>
+
+<histogram name="MobileSignInPromo.BookmarkManager.ImpressionsTilSigninButtons"
+    units="impressions">
+  <owner>jlebel@chromium.org</owner>
+  <summary>
+    Counts how many times one of the &quot;sign in&quot; buttons (any of the
+    signed-out &quot;Sign in to Chrome&quot; button, the &quot;Continue as
+    |name|&quot; button, or the &quot;Not |email|?&quot; button) is clicked per
+    impression.
+  </summary>
+</histogram>
+
+<histogram name="MobileSignInPromo.BookmarkManager.ImpressionsTilXButton"
+    units="impressions">
+  <owner>jlebel@chromium.org</owner>
+  <summary>
+    Counts how many times the explicit &quot;X&quot;-to-close button is clicked
+    per impression.
+  </summary>
+</histogram>
+
 <histogram name="MobileStartup.IntentToCreationTime" units="ms">
   <owner>twellington@chromium.org</owner>
   <summary>