diff --git a/chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/readermode/ReaderModePanel.java b/chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/readermode/ReaderModePanel.java
index 0924de21..cedcb087 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/readermode/ReaderModePanel.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/readermode/ReaderModePanel.java
@@ -21,6 +21,7 @@
 import org.chromium.chrome.browser.dom_distiller.DomDistillerTabUtils;
 import org.chromium.chrome.browser.dom_distiller.ReaderModeManagerDelegate;
 import org.chromium.chrome.browser.externalnav.ExternalNavigationHandler;
+import org.chromium.chrome.browser.rappor.RapporServiceBridge;
 import org.chromium.components.navigation_interception.NavigationParams;
 import org.chromium.content.browser.ContentViewCore;
 import org.chromium.content_public.browser.WebContents;
@@ -246,6 +247,11 @@
         if (!mTimerRunning && animatingToOpenState) {
             mStartTime = System.currentTimeMillis();
             mTimerRunning = true;
+            if (mManagerDelegate != null) {
+                String url = mManagerDelegate.getBasePageWebContents().getUrl();
+                RapporServiceBridge.sampleDomainAndRegistryFromURL(
+                        "DomDistiller.OpenPanel", url);
+            }
         } else if (mTimerRunning && !animatingToOpenState) {
             onTimerEnded();
         }
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/dom_distiller/ReaderModeManager.java b/chrome/android/java/src/org/chromium/chrome/browser/dom_distiller/ReaderModeManager.java
index bd8246b1..7fefc98 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/dom_distiller/ReaderModeManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/dom_distiller/ReaderModeManager.java
@@ -9,6 +9,7 @@
 
 import org.chromium.base.CommandLine;
 import org.chromium.base.SysUtils;
+import org.chromium.base.library_loader.LibraryLoader;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.chrome.browser.ChromeActivity;
 import org.chromium.chrome.browser.ChromeSwitches;
@@ -19,6 +20,7 @@
 import org.chromium.chrome.browser.infobar.InfoBar;
 import org.chromium.chrome.browser.infobar.InfoBarContainer;
 import org.chromium.chrome.browser.infobar.InfoBarContainer.InfoBarContainerObserver;
+import org.chromium.chrome.browser.rappor.RapporServiceBridge;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tabmodel.TabCreatorManager;
 import org.chromium.chrome.browser.tabmodel.TabModel;
@@ -315,6 +317,10 @@
         if (info != null && !info.isPanelShowRecorded()) {
             info.setIsPanelShowRecorded(true);
             recordPanelVisibilityForNavigation(true);
+            if (LibraryLoader.isInitialized()) {
+                RapporServiceBridge.sampleDomainAndRegistryFromURL(
+                        "DomDistiller.PromptPanel", info.getUrl());
+            }
         }
     }
 
diff --git a/tools/mb/mb_config.pyl b/tools/mb/mb_config.pyl
index 58d75a7..166cc9c 100644
--- a/tools/mb/mb_config.pyl
+++ b/tools/mb/mb_config.pyl
@@ -213,7 +213,6 @@
       'Win LKGR (DrM)': 'gn_release_drmemory_drfuzz_x86',
       'Win8 Tests (1)': 'none',
       'Win8 Tests (2)': 'none',
-      'WinClang': 'win_clang_debug_bot',
       'Windows Browser (DrMemory light) (1)': 'none',
       'Windows Browser (DrMemory light) (2)': 'none',
 
diff --git a/tools/metrics/rappor/rappor.xml b/tools/metrics/rappor/rappor.xml
index 495ca0bb..11d37fa4 100644
--- a/tools/metrics/rappor/rappor.xml
+++ b/tools/metrics/rappor/rappor.xml
@@ -468,6 +468,36 @@
   </summary>
 </rappor-metric>
 
+<rappor-metric name="DomDistiller.OpenPanel" type="UMA_RAPPOR_TYPE">
+  <owner>wychen@chromium.org</owner>
+  <summary>
+    The eTLD+1 of the frame URL where Reader Mode panel is opened by the
+    user.
+  </summary>
+</rappor-metric>
+
+<rappor-metric name="DomDistiller.PromptPanel" type="UMA_RAPPOR_TYPE">
+  <owner>wychen@chromium.org</owner>
+  <summary>
+    The eTLD+1 of the frame URL where Reader Mode is prompted.
+  </summary>
+</rappor-metric>
+
+<rappor-metric name="DomDistiller.OpenPanel" type="UMA_RAPPOR_TYPE">
+  <owner>wychen@chromium.org</owner>
+  <summary>
+    The eTLD+1 of the frame URL where Reader Mode panel is opened by the
+    user.
+  </summary>
+</rappor-metric>
+
+<rappor-metric name="DomDistiller.PromptPanel" type="UMA_RAPPOR_TYPE">
+  <owner>wychen@chromium.org</owner>
+  <summary>
+    The eTLD+1 of the frame URL where Reader Mode is prompted.
+  </summary>
+</rappor-metric>
+
 <rappor-metric name="Extensions.AffectedByIsolateExtensions"
     type="UMA_RAPPOR_TYPE">
   <owner>nick@chromium.org</owner>