Watch for RenderFrameHost switch in distillability

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 499804efd75587a2dddb56a9edfc9ae15882eb99..a3824cae221958e75315f302fbdb1ad514cbf734 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.VisibleForTesting;
 import org.chromium.base.library_loader.LibraryLoader;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.chrome.browser.ChromeActivity;
@@ -548,6 +549,14 @@ public class ReaderModeManager extends TabModelSelectorTabObserver
     }
 
     /**
+     * @return The ReaderModePanel for testing.
+     */
+    @VisibleForTesting
+    public ReaderModePanel getPanelForTesting() {
+        return mReaderModePanel;
+    }
+
+    /**
      * Set the callback for updating reader mode status based on whether or not the page should
      * be viewed in reader mode.
      * @param tabId The ID of the tab having its callback set.