In previous implementation, if the server does the more than one server redirects, we only record t…

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 2737b2333c113c67a6c32320b08c3ee0afa8926c..00c51d5bc6ab86aa50dc27ac2f62f9d56b7a8d80 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -55075,6 +55075,23 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="SafeBrowsing.NavigationObserver.IPAddressCleanUpCount">
+  <owner>jialiul@chromium.org</owner>
+  <summary>
+    Count of how many ResolvedIPAddresses get removed in each periodic clean up.
+    This is a rough estimation of the number of IPs associated with main frame
+    and sub-frame navigations every two minutes.
+  </summary>
+</histogram>
+
+<histogram name="SafeBrowsing.NavigationObserver.NavigationEventCleanUpCount">
+  <owner>jialiul@chromium.org</owner>
+  <summary>
+    Count of how many NavigationEvents get removed in each periodic clean up.
+    This is a rough estimation of the number of navigations every two minutes.
+  </summary>
+</histogram>
+
 <histogram name="SafeBrowsing.NotificationImageReporter.NetError"
     enum="NetErrorCodes">
   <owner>nparker@chromium.org</owner>