Support undoing offline page deletion

chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkItemsAdapter.java

 // 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.
 
 package org.chromium.chrome.browser.enhancedbookmarks;
 
 import android.content.Context;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.RecyclerView.ViewHolder;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
 import org.chromium.base.annotations.SuppressFBWarnings;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.BookmarksBridge.BookmarkItem;
 import org.chromium.chrome.browser.BookmarksBridge.BookmarkModelObserver;
 import org.chromium.chrome.browser.enhancedbookmarks.EnhancedBookmarkManager.UIState;
 import org.chromium.chrome.browser.enhancedbookmarks.EnhancedBookmarkPromoHeader.PromoHeaderShowingChangeListener;
 import org.chromium.chrome.browser.offlinepages.OfflinePageBridge;
+import org.chromium.chrome.browser.offlinepages.OfflinePageBridge.OfflinePageModelObserver;
 import org.chromium.chrome.browser.offlinepages.OfflinePageFreeUpSpaceCallback;
 import org.chromium.chrome.browser.offlinepages.OfflinePageFreeUpSpaceDialog;
 import org.chromium.chrome.browser.offlinepages.OfflinePageStorageSpaceHeader;
 import org.chromium.components.bookmarks.BookmarkId;
 
 import java.util.ArrayList;
 import java.util.List;
 
 /**
  * BaseAdapter for EnhancedBookmarkItemsContainer. It manages bookmarks to list there.
@@ skipping 39 matching lines @@
                 }
             }
         }
 
         @Override
         public void bookmarkModelChanged() {
             mDelegate.notifyStateChange(EnhancedBookmarkItemsAdapter.this);
         }
     };
 
+    private OfflinePageModelObserver mOfflinePageModelObserver;
+
     EnhancedBookmarkItemsAdapter(Context context) {
         mContext = context;
 
         mSections = new ArrayList<>();
         mSections.add(mPromoHeaderSection);
         mSections.add(mOfflineStorageSection);
         mSections.add(mFolderDividerSection);
         mSections.add(mFolderSection);
         mSections.add(mBookmarkDividerSection);
         mSections.add(mBookmarkSection);
@@ skipping 175 matching lines @@
     // EnhancedBookmarkUIObserver implementations.
 
     @Override
     public void onEnhancedBookmarkDelegateInitialized(EnhancedBookmarkDelegate delegate) {
         mDelegate = delegate;
         mDelegate.addUIObserver(this);
         mDelegate.getModel().addObserver(mBookmarkModelObserver);
         mPromoHeaderManager = new EnhancedBookmarkPromoHeader(mContext, this);
         OfflinePageBridge offlinePageBridge = mDelegate.getModel().getOfflinePageBridge();
         if (offlinePageBridge != null) {
+            mOfflinePageModelObserver = new OfflinePageModelObserver() {

[Ian Wen, 2015/10/13 00:35:04]

Q: why a model observer is added to this class? I suppose undo should only need
to live in model layer?

[jianli, 2015/10/13 00:57:05]

The model layer doesn't know how to trigger updating the UI. When a bookmark
with offline copy is being restored from the deletion, we need to update the
bookmark page, esp when it shows "Saved offline" view. The "Saved offline" view
will only list all bookmark items that have offline copies. When an offline copy
is restored, it will take some time to update the offline metadata store and
only after this "Saved offline" view can see the restored offline item. This is
the reason we need to listen to offline model change event and refresh the UI
here.

+                @Override
+                public void offlinePageModelChanged() {
+                    mDelegate.notifyStateChange(EnhancedBookmarkItemsAdapter.this);
+                }
+            };
+            offlinePageBridge.addObserver(mOfflinePageModelObserver);
+
             mOfflineStorageHeader = new OfflinePageStorageSpaceHeader(
                     mContext, offlinePageBridge, new OfflinePageFreeUpSpaceCallback() {
                         @Override
                         public void onFreeUpSpaceDone() {
                             refreshOfflinePagesFilterView();
                             mDelegate.getSnackbarManager().showSnackbar(
                                     OfflinePageFreeUpSpaceDialog.createStorageClearedSnackbar(
                                             mContext));
                         }
 
                         @Override
                         public void onFreeUpSpaceCancelled() {
                             // No need to refresh, as result outcome should be the same here.
                         }
                     });
         }
     }
 
     @Override
     public void onDestroy() {
         mDelegate.removeUIObserver(this);
         mDelegate.getModel().removeObserver(mBookmarkModelObserver);
         mPromoHeaderManager.destroy();
-        if (mOfflineStorageHeader != null) {
+
+        OfflinePageBridge offlinePageBridge = mDelegate.getModel().getOfflinePageBridge();
+        if (offlinePageBridge != null) {
+            offlinePageBridge.removeObserver(mOfflinePageModelObserver);
             mOfflineStorageHeader.destroy();
         }
     }
 
     @Override
     public void onAllBookmarksStateSet() {
         setBookmarks(null, mDelegate.getModel().getAllBookmarkIDsOrderedByCreationDate());
     }
 
     @Override
@@ skipping 35 matching lines @@
             }
         }
     }
 
     private void refreshOfflinePagesFilterView() {
         if (mDelegate.getCurrentState() != UIState.STATE_FILTER) return;
         setBookmarks(null,
                 mDelegate.getModel().getBookmarkIDsByFilter(EnhancedBookmarkFilter.OFFLINE_PAGES));
     }
 }