The Tor Browser: mobile/android/base/home/TopSitesPanel.java@b8a032363ba2 (annotated)

mobile/android/base/home/TopSitesPanel.java@b8a032363ba2 (annotated)

mobile/android/base/home/TopSitesPanel.java

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 package org.mozilla.gecko.home;
 import java.util.ArrayList;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.Map;
 import org.mozilla.gecko.R;
 import org.mozilla.gecko.Telemetry;
 import org.mozilla.gecko.TelemetryContract;
 import org.mozilla.gecko.db.BrowserContract.Combined;
 import org.mozilla.gecko.db.BrowserContract.Thumbnails;
 import org.mozilla.gecko.db.BrowserDB;
 import org.mozilla.gecko.db.BrowserDB.URLColumns;
 import org.mozilla.gecko.db.TopSitesCursorWrapper;
 import org.mozilla.gecko.favicons.Favicons;
 import org.mozilla.gecko.favicons.OnFaviconLoadedListener;
 import org.mozilla.gecko.gfx.BitmapUtils;
 import org.mozilla.gecko.home.HomePager.OnUrlOpenListener;
 import org.mozilla.gecko.home.PinSiteDialog.OnSiteSelectedListener;
 import org.mozilla.gecko.home.TopSitesGridView.OnEditPinnedSiteListener;
 import org.mozilla.gecko.home.TopSitesGridView.TopSitesGridContextMenuInfo;
 import org.mozilla.gecko.util.ThreadUtils;
 import android.app.Activity;
 import android.content.ContentResolver;
 import android.content.Context;
 import android.content.res.Configuration;
 import android.database.Cursor;
 import android.graphics.Bitmap;
 import android.net.Uri;
 import android.os.Bundle;
 import android.support.v4.app.FragmentManager;
 import android.support.v4.app.LoaderManager.LoaderCallbacks;
 import android.support.v4.content.AsyncTaskLoader;
 import android.support.v4.content.Loader;
 import android.support.v4.widget.CursorAdapter;
 import android.text.TextUtils;
 import android.util.Log;
 import android.view.ContextMenu;
 import android.view.ContextMenu.ContextMenuInfo;
 import android.view.LayoutInflater;
 import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.AdapterView;
 import android.widget.ListView;
 /**
  * Fragment that displays frecency search results in a ListView.
  */
 public class TopSitesPanel extends HomeFragment {
     // Logging tag name
     private static final String LOGTAG = "GeckoTopSitesPanel";
     // Cursor loader ID for the top sites
     private static final int LOADER_ID_TOP_SITES = 0;
     // Loader ID for thumbnails
     private static final int LOADER_ID_THUMBNAILS = 1;
     // Key for thumbnail urls
     private static final String THUMBNAILS_URLS_KEY = "urls";
     // Adapter for the list of top sites
     private VisitedAdapter mListAdapter;
     // Adapter for the grid of top sites
     private TopSitesGridAdapter mGridAdapter;
     // List of top sites
     private HomeListView mList;
     // Grid of top sites
     private TopSitesGridView mGrid;
     // Callbacks used for the search and favicon cursor loaders
     private CursorLoaderCallbacks mCursorLoaderCallbacks;
     // Callback for thumbnail loader
     private ThumbnailsLoaderCallbacks mThumbnailsLoaderCallbacks;
     // Listener for editing pinned sites.
     private EditPinnedSiteListener mEditPinnedSiteListener;
     // On URL open listener
     private OnUrlOpenListener mUrlOpenListener;
     // Max number of entries shown in the grid from the cursor.
     private int mMaxGridEntries;
     // Time in ms until the Gecko thread is reset to normal priority.
     private static final long PRIORITY_RESET_TIMEOUT = 10000;
     public static TopSitesPanel newInstance() {
         return new TopSitesPanel();
     }
     public TopSitesPanel() {
         mUrlOpenListener = null;
     }
     private static boolean logDebug = Log.isLoggable(LOGTAG, Log.DEBUG);
     private static boolean logVerbose = Log.isLoggable(LOGTAG, Log.VERBOSE);
     private static void debug(final String message) {
         if (logDebug) {
             Log.d(LOGTAG, message);
         }
     }
     private static void trace(final String message) {
         if (logVerbose) {
             Log.v(LOGTAG, message);
         }
     }
     @Override
     public void onAttach(Activity activity) {
         super.onAttach(activity);
         mMaxGridEntries = activity.getResources().getInteger(R.integer.number_of_top_sites);
         try {
             mUrlOpenListener = (OnUrlOpenListener) activity;
         } catch (ClassCastException e) {
             throw new ClassCastException(activity.toString()
                     + " must implement HomePager.OnUrlOpenListener");
         }
     }
     @Override
     public void onDetach() {
         super.onDetach();
         mUrlOpenListener = null;
     }
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         final View view = inflater.inflate(R.layout.home_top_sites_panel, container, false);
         mList = (HomeListView) view.findViewById(R.id.list);
         mGrid = new TopSitesGridView(getActivity());
         mList.addHeaderView(mGrid);
         return view;
     }
     @Override
     public void onViewCreated(View view, Bundle savedInstanceState) {
         mEditPinnedSiteListener = new EditPinnedSiteListener();
         mList.setTag(HomePager.LIST_TAG_TOP_SITES);
         mList.setHeaderDividersEnabled(false);
         mList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
             @Override
             public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                 final ListView list = (ListView) parent;
                 final int headerCount = list.getHeaderViewsCount();
                 if (position < headerCount) {
                     // The click is on a header, don't do anything.
                     return;
                 }
                 // Absolute position for the adapter.
                 position += (mGridAdapter.getCount() - headerCount);
                 final Cursor c = mListAdapter.getCursor();
                 if (c == null || !c.moveToPosition(position)) {
                     return;
                 }
                 final String url = c.getString(c.getColumnIndexOrThrow(URLColumns.URL));
                 Telemetry.sendUIEvent(TelemetryContract.Event.LOAD_URL, TelemetryContract.Method.LIST_ITEM);
                 // This item is a TwoLinePageRow, so we allow switch-to-tab.
                 mUrlOpenListener.onUrlOpen(url, EnumSet.of(OnUrlOpenListener.Flags.ALLOW_SWITCH_TO_TAB));
             }
         });
         mList.setContextMenuInfoFactory(new HomeContextMenuInfo.Factory() {
             @Override
             public HomeContextMenuInfo makeInfoForCursor(View view, int position, long id, Cursor cursor) {
                 final HomeContextMenuInfo info = new HomeContextMenuInfo(view, position, id);
                 info.url = cursor.getString(cursor.getColumnIndexOrThrow(Combined.URL));
                 info.title = cursor.getString(cursor.getColumnIndexOrThrow(Combined.TITLE));
                 info.historyId = cursor.getInt(cursor.getColumnIndexOrThrow(Combined.HISTORY_ID));
                 final int bookmarkIdCol = cursor.getColumnIndexOrThrow(Combined.BOOKMARK_ID);
                 if (cursor.isNull(bookmarkIdCol)) {
                     // If this is a combined cursor, we may get a history item without a
                     // bookmark, in which case the bookmarks ID column value will be null.
                     info.bookmarkId =  -1;
                 } else {
                     info.bookmarkId = cursor.getInt(bookmarkIdCol);
                 }
                 return info;
             }
         });
         mGrid.setOnUrlOpenListener(mUrlOpenListener);
         mGrid.setOnEditPinnedSiteListener(mEditPinnedSiteListener);
         registerForContextMenu(mList);
         registerForContextMenu(mGrid);
     }
     @Override
     public void onDestroyView() {
         super.onDestroyView();
         // Discard any additional item clicks on the list
         // as the panel is getting destroyed (see bug 930160).
         mList.setOnItemClickListener(null);
         mList = null;
         mGrid = null;
         mListAdapter = null;
         mGridAdapter = null;
     }
     @Override
     public void onConfigurationChanged(Configuration newConfig) {
         super.onConfigurationChanged(newConfig);
         // Detach and reattach the fragment as the layout changes.
         if (isVisible()) {
             getFragmentManager().beginTransaction()
                                 .detach(this)
                                 .attach(this)
                                 .commitAllowingStateLoss();
         }
     }
     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);
         final Activity activity = getActivity();
         // Setup the top sites grid adapter.
         mGridAdapter = new TopSitesGridAdapter(activity, null);
         mGrid.setAdapter(mGridAdapter);
         // Setup the top sites list adapter.
         mListAdapter = new VisitedAdapter(activity, null);
         mList.setAdapter(mListAdapter);
         // Create callbacks before the initial loader is started
         mCursorLoaderCallbacks = new CursorLoaderCallbacks();
         mThumbnailsLoaderCallbacks = new ThumbnailsLoaderCallbacks();
         loadIfVisible();
     }
     @Override
     public void onCreateContextMenu(ContextMenu menu, View view, ContextMenuInfo menuInfo) {
         if (menuInfo == null) {
             return;
         }
         if (!(menuInfo instanceof TopSitesGridContextMenuInfo)) {
             // Long pressed item was not a Top Sites GridView item. Superclass
             // can handle this.
             super.onCreateContextMenu(menu, view, menuInfo);
             return;
         }
         // Long pressed item was a Top Sites GridView item, handle it.
         MenuInflater inflater = new MenuInflater(view.getContext());
         inflater.inflate(R.menu.home_contextmenu, menu);
         // Hide ununsed menu items.
         menu.findItem(R.id.home_open_in_reader).setVisible(false);
         menu.findItem(R.id.home_edit_bookmark).setVisible(false);
         menu.findItem(R.id.home_remove).setVisible(false);
         TopSitesGridContextMenuInfo info = (TopSitesGridContextMenuInfo) menuInfo;
         menu.setHeaderTitle(info.getDisplayTitle());
         if (!TextUtils.isEmpty(info.url)) {
             if (info.isPinned) {
                 menu.findItem(R.id.top_sites_pin).setVisible(false);
             } else {
                 menu.findItem(R.id.top_sites_unpin).setVisible(false);
             }
         } else {
             menu.findItem(R.id.home_open_new_tab).setVisible(false);
             menu.findItem(R.id.home_open_private_tab).setVisible(false);
             menu.findItem(R.id.top_sites_pin).setVisible(false);
             menu.findItem(R.id.top_sites_unpin).setVisible(false);
         }
     }
     @Override
     public boolean onContextItemSelected(MenuItem item) {
         if (super.onContextItemSelected(item)) {
             // HomeFragment was able to handle to selected item.
             return true;
         }
         ContextMenuInfo menuInfo = item.getMenuInfo();
         if (menuInfo == null || !(menuInfo instanceof TopSitesGridContextMenuInfo)) {
             return false;
         }
         TopSitesGridContextMenuInfo info = (TopSitesGridContextMenuInfo) menuInfo;
         final Activity activity = getActivity();
         final int itemId = item.getItemId();
         if (itemId == R.id.top_sites_pin) {
             final String url = info.url;
             final String title = info.title;
             final int position = info.position;
             final Context context = getActivity().getApplicationContext();
             ThreadUtils.postToBackgroundThread(new Runnable() {
                 @Override
                 public void run() {
                     BrowserDB.pinSite(context.getContentResolver(), url, title, position);
                 }
             });
             Telemetry.sendUIEvent(TelemetryContract.Event.TOP_SITES_PIN);
             return true;
         }
         if (itemId == R.id.top_sites_unpin) {
             final int position = info.position;
             final Context context = getActivity().getApplicationContext();
             ThreadUtils.postToBackgroundThread(new Runnable() {
                 @Override
                 public void run() {
                     BrowserDB.unpinSite(context.getContentResolver(), position);
                 }
             });
             Telemetry.sendUIEvent(TelemetryContract.Event.TOP_SITES_UNPIN);
             return true;
         }
         if (itemId == R.id.top_sites_edit) {
             // Decode "user-entered" URLs before showing them.
             mEditPinnedSiteListener.onEditPinnedSite(info.position, decodeUserEnteredUrl(info.url));
             Telemetry.sendUIEvent(TelemetryContract.Event.TOP_SITES_EDIT);
             return true;
         }
         return false;
     }
     @Override
     protected void load() {
         getLoaderManager().initLoader(LOADER_ID_TOP_SITES, null, mCursorLoaderCallbacks);
         // Since this is the primary fragment that loads whenever about:home is
         // visited, we want to load it as quickly as possible. Heavy load on
         // the Gecko thread can slow down the time it takes for thumbnails to
         // appear, especially during startup (bug 897162). By minimizing the
         // Gecko thread priority, we ensure that the UI appears quickly. The
         // priority is reset to normal once thumbnails are loaded.
         ThreadUtils.reduceGeckoPriority(PRIORITY_RESET_TIMEOUT);
     }
     static String encodeUserEnteredUrl(String url) {
         return Uri.fromParts("user-entered", url, null).toString();
     }
     /**
      * Listener for editing pinned sites.
      */
     private class EditPinnedSiteListener implements OnEditPinnedSiteListener,
                                                     OnSiteSelectedListener {
         // Tag for the PinSiteDialog fragment.
         private static final String TAG_PIN_SITE = "pin_site";
         // Position of the pin.
         private int mPosition;
         @Override
         public void onEditPinnedSite(int position, String searchTerm) {
             mPosition = position;
             final FragmentManager manager = getChildFragmentManager();
             PinSiteDialog dialog = (PinSiteDialog) manager.findFragmentByTag(TAG_PIN_SITE);
             if (dialog == null) {
                 dialog = PinSiteDialog.newInstance();
             }
             dialog.setOnSiteSelectedListener(this);
             dialog.setSearchTerm(searchTerm);
             dialog.show(manager, TAG_PIN_SITE);
         }
         @Override
         public void onSiteSelected(final String url, final String title) {
             final int position = mPosition;
             final Context context = getActivity().getApplicationContext();
             ThreadUtils.postToBackgroundThread(new Runnable() {
                 @Override
                 public void run() {
                     BrowserDB.pinSite(context.getContentResolver(), url, title, position);
                 }
             });
         }
     }
     private void updateUiFromCursor(Cursor c) {
         mList.setHeaderDividersEnabled(c != null && c.getCount() > mMaxGridEntries);
     }
     private static class TopSitesLoader extends SimpleCursorLoader {
         // Max number of search results
         private static final int SEARCH_LIMIT = 30;
         private int mMaxGridEntries;
         public TopSitesLoader(Context context) {
             super(context);
             mMaxGridEntries = context.getResources().getInteger(R.integer.number_of_top_sites);
         }
         @Override
         public Cursor loadCursor() {
             trace("TopSitesLoader.loadCursor()");
             return BrowserDB.getTopSites(getContext().getContentResolver(), mMaxGridEntries, SEARCH_LIMIT);
         }
     }
     private class VisitedAdapter extends CursorAdapter {
         public VisitedAdapter(Context context, Cursor cursor) {
             super(context, cursor, 0);
         }
         @Override
         public int getCount() {
             return Math.max(0, super.getCount() - mMaxGridEntries);
         }
         @Override
         public Object getItem(int position) {
             return super.getItem(position + mMaxGridEntries);
         }
         @Override
         public void bindView(View view, Context context, Cursor cursor) {
             final int position = cursor.getPosition();
             cursor.moveToPosition(position + mMaxGridEntries);
             final TwoLinePageRow row = (TwoLinePageRow) view;
             row.updateFromCursor(cursor);
         }
         @Override
         public View newView(Context context, Cursor cursor, ViewGroup parent) {
             return LayoutInflater.from(context).inflate(R.layout.bookmark_item_row, parent, false);
         }
     }
     public class TopSitesGridAdapter extends CursorAdapter {
         // Cache to store the thumbnails.
         // Ensure that this is only accessed from the UI thread.
         private Map<String, Bitmap> mThumbnails;
         public TopSitesGridAdapter(Context context, Cursor cursor) {
             super(context, cursor, 0);
         }
         @Override
         public int getCount() {
             return Math.min(mMaxGridEntries, super.getCount());
         }
         @Override
         protected void onContentChanged() {
             // Don't do anything. We don't want to regenerate every time
             // our database is updated.
             return;
         }
         /**
          * Update the thumbnails returned by the db.
          *
          * @param thumbnails A map of urls and their thumbnail bitmaps.
          */
         public void updateThumbnails(Map<String, Bitmap> thumbnails) {
             mThumbnails = thumbnails;
             final int count = mGrid.getChildCount();
             for (int i = 0; i < count; i++) {
                 TopSitesGridItemView gridItem = (TopSitesGridItemView) mGrid.getChildAt(i);
                 // All the views have already got their initial state at this point.
                 // This will force each view to load favicons for the missing
                 // thumbnails if necessary.
                 gridItem.markAsDirty();
             }
             notifyDataSetChanged();
         }
         @Override
         public void bindView(View bindView, Context context, Cursor cursor) {
             String url = "";
             String title = "";
             boolean pinned = false;
             // Cursor is already moved to required position.
             if (!cursor.isAfterLast()) {
                 url = cursor.getString(cursor.getColumnIndexOrThrow(URLColumns.URL));
                 title = cursor.getString(cursor.getColumnIndexOrThrow(URLColumns.TITLE));
                 pinned = ((TopSitesCursorWrapper) cursor).isPinned();
             }
             final TopSitesGridItemView view = (TopSitesGridItemView) bindView;
             // If there is no url, then show "add bookmark".
             if (TextUtils.isEmpty(url)) {
                 // Wait until thumbnails are loaded before showing anything.
                 if (mThumbnails != null) {
                     view.blankOut();
                 }
                 return;
             }
             // Show the thumbnail, if any.
             Bitmap thumbnail = (mThumbnails != null ? mThumbnails.get(url) : null);
             // Debounce bindView calls to avoid redundant redraws and favicon
             // fetches.
             final boolean updated = view.updateState(title, url, pinned, thumbnail);
             // If thumbnails are still being loaded, don't try to load favicons
             // just yet. If we sent in a thumbnail, we're done now.
             if (mThumbnails == null || thumbnail != null) {
                 return;
             }
             // Thumbnails are delivered late, so we can't short-circuit any
             // sooner than this. But we can avoid a duplicate favicon
             // fetch...
             if (!updated) {
                 debug("bindView called twice for same values; short-circuiting.");
                 return;
             }
             // If we have no thumbnail, attempt to show a Favicon instead.
             LoadIDAwareFaviconLoadedListener listener = new LoadIDAwareFaviconLoadedListener(view);
             final int loadId = Favicons.getSizedFaviconForPageFromLocal(url, listener);
             if (loadId == Favicons.LOADED) {
                 // Great!
                 return;
             }
             // Otherwise, do this until the async lookup returns.
             view.displayThumbnail(R.drawable.favicon);
             // Give each side enough information to shake hands later.
             listener.setLoadId(loadId);
             view.setLoadId(loadId);
         }
         @Override
         public View newView(Context context, Cursor cursor, ViewGroup parent) {
             return new TopSitesGridItemView(context);
         }
     }
     private static class LoadIDAwareFaviconLoadedListener implements OnFaviconLoadedListener {
         private volatile int loadId = Favicons.NOT_LOADING;
         private final TopSitesGridItemView view;
         public LoadIDAwareFaviconLoadedListener(TopSitesGridItemView view) {
             this.view = view;
         }
         public void setLoadId(int id) {
             this.loadId = id;
         }
         @Override
         public void onFaviconLoaded(String url, String faviconURL, Bitmap favicon) {
             if (TextUtils.equals(this.view.getUrl(), url)) {
                 this.view.displayFavicon(favicon, faviconURL, this.loadId);
             }
         }
     }
     private class CursorLoaderCallbacks implements LoaderCallbacks<Cursor> {
         @Override
         public Loader<Cursor> onCreateLoader(int id, Bundle args) {
             trace("Creating TopSitesLoader: " + id);
             return new TopSitesLoader(getActivity());
         }
         /**
          * This method is called *twice* in some circumstances.
          *
          * If you try to avoid that through some kind of boolean flag,
          * sometimes (e.g., returning to the activity) you'll *not* be called
          * twice, and thus you'll never draw thumbnails.
          *
          * The root cause is TopSitesLoader.loadCursor being called twice.
          * Why that is... dunno.
          */
         @Override
         public void onLoadFinished(Loader<Cursor> loader, Cursor c) {
             debug("onLoadFinished: " + c.getCount() + " rows.");
             mListAdapter.swapCursor(c);
             mGridAdapter.swapCursor(c);
             updateUiFromCursor(c);
             final int col = c.getColumnIndexOrThrow(URLColumns.URL);
             // Load the thumbnails.
             // Even though the cursor we're given is supposed to be fresh,
             // we get a bad first value unless we reset its position.
             // Using move(-1) and moveToNext() doesn't work correctly under
             // rotation, so we use moveToFirst.
             if (!c.moveToFirst()) {
                 return;
             }
             final ArrayList<String> urls = new ArrayList<String>();
             int i = 1;
             do {
                 urls.add(c.getString(col));
             } while (i++ < mMaxGridEntries && c.moveToNext());
             if (urls.isEmpty()) {
                 return;
             }
             Bundle bundle = new Bundle();
             bundle.putStringArrayList(THUMBNAILS_URLS_KEY, urls);
             getLoaderManager().restartLoader(LOADER_ID_THUMBNAILS, bundle, mThumbnailsLoaderCallbacks);
         }
         @Override
         public void onLoaderReset(Loader<Cursor> loader) {
             if (mListAdapter != null) {
                 mListAdapter.swapCursor(null);
             }
             if (mGridAdapter != null) {
                 mGridAdapter.swapCursor(null);
             }
         }
     }
     /**
      * An AsyncTaskLoader to load the thumbnails from a cursor.
      */
     private static class ThumbnailsLoader extends AsyncTaskLoader<Map<String, Bitmap>> {
         private Map<String, Bitmap> mThumbnails;
         private ArrayList<String> mUrls;
         public ThumbnailsLoader(Context context, ArrayList<String> urls) {
             super(context);
             mUrls = urls;
         }
         @Override
         public Map<String, Bitmap> loadInBackground() {
             if (mUrls == null || mUrls.size() == 0) {
                 return null;
             }
             // Query the DB for thumbnails.
             final ContentResolver cr = getContext().getContentResolver();
             final Cursor cursor = BrowserDB.getThumbnailsForUrls(cr, mUrls);
             if (cursor == null) {
                 return null;
             }
             final Map<String, Bitmap> thumbnails = new HashMap<String, Bitmap>();
             try {
                 final int urlIndex = cursor.getColumnIndexOrThrow(Thumbnails.URL);
                 final int dataIndex = cursor.getColumnIndexOrThrow(Thumbnails.DATA);
                 while (cursor.moveToNext()) {
                     String url = cursor.getString(urlIndex);
                     // This should never be null, but if it is...
                     final byte[] b = cursor.getBlob(dataIndex);
                     if (b == null) {
                         continue;
                     }
                     final Bitmap bitmap = BitmapUtils.decodeByteArray(b);
                     // Our thumbnails are never null, so if we get a null decoded
                     // bitmap, it's because we hit an OOM or some other disaster.
                     // Give up immediately rather than hammering on.
                     if (bitmap == null) {
                         Log.w(LOGTAG, "Aborting thumbnail load; decode failed.");
                         break;
                     }
                     thumbnails.put(url, bitmap);
                 }
             } finally {
                 cursor.close();
             }
             return thumbnails;
         }
         @Override
         public void deliverResult(Map<String, Bitmap> thumbnails) {
             if (isReset()) {
                 mThumbnails = null;
                 return;
             }
             mThumbnails = thumbnails;
             if (isStarted()) {
                 super.deliverResult(thumbnails);
             }
         }
         @Override
         protected void onStartLoading() {
             if (mThumbnails != null) {
                 deliverResult(mThumbnails);
             }
             if (takeContentChanged() || mThumbnails == null) {
                 forceLoad();
             }
         }
         @Override
         protected void onStopLoading() {
             cancelLoad();
         }
         @Override
         public void onCanceled(Map<String, Bitmap> thumbnails) {
             mThumbnails = null;
         }
         @Override
         protected void onReset() {
             super.onReset();
             // Ensure the loader is stopped.
             onStopLoading();
             mThumbnails = null;
         }
     }
     /**
      * Loader callbacks for the thumbnails on TopSitesGridView.
      */
     private class ThumbnailsLoaderCallbacks implements LoaderCallbacks<Map<String, Bitmap>> {
         @Override
         public Loader<Map<String, Bitmap>> onCreateLoader(int id, Bundle args) {
             return new ThumbnailsLoader(getActivity(), args.getStringArrayList(THUMBNAILS_URLS_KEY));
         }
         @Override
         public void onLoadFinished(Loader<Map<String, Bitmap>> loader, Map<String, Bitmap> thumbnails) {
             if (mGridAdapter != null) {
                 mGridAdapter.updateThumbnails(thumbnails);
             }
             // Once thumbnails have finished loading, the UI is ready. Reset
             // Gecko to normal priority.
             ThreadUtils.resetGeckoPriority();
         }
         @Override
         public void onLoaderReset(Loader<Map<String, Bitmap>> loader) {
             if (mGridAdapter != null) {
                 mGridAdapter.updateThumbnails(null);
             }
         }
     }
 }

The Tor Browser / annotate

mobile/android/base/home/TopSitesPanel.java@b8a032363ba2 (annotated)

mobile/android/base/home/TopSitesPanel.java