Test that base page is available in Reader Mode

chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/readermode/ReaderModePanel.java

Index: chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/readermode/ReaderModePanel.java
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 d83ec64e09761e556f06bfa10fa12f6787b89b67..0b517df649530241a0aaf276e69d5bcaeaa0a027 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
@@ -86,10 +86,16 @@ public class ReaderModePanel extends OverlayPanel {
                 mContentViewDelegate.setOverlayPanelContentViewCore(contentView);
 
                 WebContents distilledWebContents = contentView.getWebContents();
-                if (distilledWebContents == null) return;
+                if (distilledWebContents == null) {
+                    closePanel(StateChangeReason.UNKNOWN, false);
+                    return;
+                }
 
                 WebContents sourceWebContents = mManagerDelegate.getBasePageWebContents();
-                if (sourceWebContents == null) return;
+                if (sourceWebContents == null) {
+                    closePanel(StateChangeReason.UNKNOWN, false);
+                    return;
+                }
 
                 DomDistillerTabUtils.distillAndView(sourceWebContents, distilledWebContents);
             }
@@ -255,7 +261,7 @@ public class ReaderModePanel extends OverlayPanel {
         if (!mTimerRunning && animatingToOpenState) {
             mStartTime = System.currentTimeMillis();
             mTimerRunning = true;
-            if (mManagerDelegate != null) {
+            if (mManagerDelegate != null && mManagerDelegate.getBasePageWebContents() != null) {
                 String url = mManagerDelegate.getBasePageWebContents().getUrl();
                 RapporServiceBridge.sampleDomainAndRegistryFromURL(
                         "DomDistiller.OpenPanel", url);