Record the depth of the block frame.

Bug: 850328
Change-Id: I7bc5fcd828f7f47230c4c967a28fb24525fd59b6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1838382
Commit-Queue: Yilkal Abe <yilkal@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704462}

chrome/browser/supervised_user/supervised_user_navigation_observer.cc

@@ -132,6 +132,12 @@ void SupervisedUserNavigationObserver::DidFinishLoad(
 
     UMA_HISTOGRAM_COUNTS_1000("ManagedUsers.BlockedIframeCount", count);
   }
+
+  if (base::Contains(supervised_user_interstitials_,
+                     render_frame_host->GetFrameTreeNodeId())) {
+    UMA_HISTOGRAM_COUNTS_1000("ManagedUsers.BlockedFrameDepth",
+                              render_frame_host->GetFrameDepth());
+  }
 }
 
 void SupervisedUserNavigationObserver::OnURLFilterChanged() {

tools/metrics/histograms/histograms.xml

@@ -59239,6 +59239,16 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="ManagedUsers.BlockedFrameDepth" units="depth"
+    expires_after="M85">
+  <owner>yilkal@chromium.org</owner>
+  <owner>michaelpg@chromium.org</owner>
+  <summary>
+    The depth of blocked frame in the frame tree. The value is recorded when the
+    renderer frame hosting the blocking page finishes loading.
+  </summary>
+</histogram>
+
 <histogram name="ManagedUsers.BlockedIframeCount" units="iframes"
     expires_after="M85">
   <owner>yilkal@chromium.org</owner>