Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/bookmarkswidget/BookmarkWidgetUpdateListener.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.bookmarkswidget;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.database.ContentObserver;
+import android.os.Handler;
+
+import org.chromium.chrome.browser.ChromeBrowserProvider;
+import org.chromium.sync.AndroidSyncSettings;
+
+/**
+ * Encapsulates the different observers that can cause a widget update.
+ */
+public class BookmarkWidgetUpdateListener {
+    private static final String TAG = "BookmarkWidgetUpdateListener";
+
+    /**
+     * Notifies about the different kinds of updates that affect the bookmarks widget.
+     */
+    public interface UpdateListener {
+        /**
+         * Called when the was a change in the bookmark model.
+         */
+        public void onBookmarkModelUpdated();
+
+        /**
+         * Called when the app sync enabled status has changed.
+         *
+         * @param enabled New state of the sync setting after the change.
+         */
+        public void onSyncEnabledStatusUpdated(boolean enabled);
+
+        /**
+         * Called when a page thumbnail has been updated or created.
+         */
+        public void onThumbnailUpdated(String url);
+    }
+
+    /**
+     * Handles changes in the bookmarks.
+     */
+    private class BookmarkUpdateObserver extends ContentObserver {
+        public BookmarkUpdateObserver() {
+            super(new Handler());
+        }
+
+        @Override
+        public void onChange(boolean selfChange) {
+            if (mListener != null) mListener.onBookmarkModelUpdated();
+        }
+    }
+
+    /**
+     * Handles changes in the sync settings.
+     */
+    private class SyncUpdateObserver implements AndroidSyncSettings.AndroidSyncSettingsObserver {
+        private boolean mIsSyncEnabled;
+
+        public SyncUpdateObserver() {
+            AndroidSyncSettings.registerObserver(mContext, this);
+            mIsSyncEnabled = AndroidSyncSettings.isSyncEnabled(mContext);
+        }
+
+        @Override
+        public void androidSyncSettingsChanged() {
+            boolean newSyncStatus = AndroidSyncSettings.isSyncEnabled(mContext);
+            if (mIsSyncEnabled != newSyncStatus) {
+                mIsSyncEnabled = newSyncStatus;
+                if (mListener != null) mListener.onSyncEnabledStatusUpdated(newSyncStatus);
+            }
+        }
+    }
+
+    private final Context mContext;
+    private UpdateListener mListener;
+    private BookmarkUpdateObserver mBookmarkUpdateObserver;
+    private AndroidSyncSettings.AndroidSyncSettingsObserver mSyncObserver;
+
+    public BookmarkWidgetUpdateListener(Context context, UpdateListener listener) {
+        mContext = context;
+
+        if (listener == null) return;
+        mListener = listener;
+
+        // Register observers for bookmark and sync state updates.
+        ContentResolver contentResolver = mContext.getContentResolver();
+        mBookmarkUpdateObserver = new BookmarkUpdateObserver();
+        contentResolver.registerContentObserver(
+                ChromeBrowserProvider.getBookmarksApiUri(mContext), true,
+                mBookmarkUpdateObserver);
+
+        mSyncObserver = new SyncUpdateObserver();
+    }
+
+    public void destroy() {
+        if (mListener == null) return;
+
+        // Unregister observers.
+        ContentResolver contentResolver = mContext.getContentResolver();
+        contentResolver.unregisterContentObserver(mBookmarkUpdateObserver);
+        AndroidSyncSettings.unregisterObserver(mContext, mSyncObserver);
+        mListener = null;
+    }
+}