Record domains where Reader Mode is prompted or opened

chrome/android/java/src/org/chromium/chrome/browser/dom_distiller/ReaderModeManager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/dom_distiller/ReaderModeManager.java
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 bd8246b11c21bdfdbbeac397196adf1b45d989b4..7fefc98d6bd9e4b6e3baec5fc8d5d4853b448fd9 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 android.text.TextUtils;
 
 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.device.DeviceClassManager;
 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 @@ public class ReaderModeManager extends TabModelSelectorTabObserver
         if (info != null && !info.isPanelShowRecorded()) {
             info.setIsPanelShowRecorded(true);
             recordPanelVisibilityForNavigation(true);
+            if (LibraryLoader.isInitialized()) {
+                RapporServiceBridge.sampleDomainAndRegistryFromURL(
+                        "DomDistiller.PromptPanel", info.getUrl());
+            }
         }
     }