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

chrome/browser/android/offline_pages/offline_page_bridge.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_BRIDGE_H_
 #define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_BRIDGE_H_
 
 #include <stdint.h>
 
 #include "base/android/jni_android.h"
@@ skipping 107 matching lines @@
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj,
       const base::android::JavaParamRef<jobject>& j_callback_obj);
 
   void RemoveRequestsFromQueue(
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj,
       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:
   void NotifyIfDoneLoading() const;
 
   base::android::ScopedJavaLocalRef<jobject> CreateClientId(
       JNIEnv* env,
       const ClientId& clientId) const;
 
   base::android::ScopedJavaGlobalRef<jobject> java_ref_;
   // Not owned.
   content::BrowserContext* browser_context_;
   // Not owned.
   OfflinePageModel* offline_page_model_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageBridge);
 };
 
 bool RegisterOfflinePageBridge(JNIEnv* env);
 
 }  // namespace android
 }  // namespace offline_pages
 
 #endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_BRIDGE_H_