Only show Last N Pages in the UI when the corresponding tab is visible.

chrome/browser/android/offline_pages/offline_page_bridge.h

Index: chrome/browser/android/offline_pages/offline_page_bridge.h
diff --git a/chrome/browser/android/offline_pages/offline_page_bridge.h b/chrome/browser/android/offline_pages/offline_page_bridge.h
index f0ee0d170eee51e091cc8e80ff23a49231c2586c..96790c41954df988743ac172e81600b1eefb173f 100644
--- a/chrome/browser/android/offline_pages/offline_page_bridge.h
+++ b/chrome/browser/android/offline_pages/offline_page_bridge.h
@@ -125,6 +125,13 @@ class OfflinePageBridge : public OfflinePageModel::Observer,
       const base::android::JavaParamRef<jlongArray>& j_request_ids_array,
       const base::android::JavaParamRef<jobject>& j_callback_obj);
 
+  void RegisterRecentTab(JNIEnv* env,
+                         const base::android::JavaParamRef<jobject>& obj,
+                         int tab_id);
+  void UnregisterRecentTab(JNIEnv* env,
+                           const base::android::JavaParamRef<jobject>& obj,
+                           int tab_id);
+
   base::android::ScopedJavaGlobalRef<jobject> java_ref() { return java_ref_; }
 
  private: