[Sync] Restore previous session if no tabbed windows present

chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java

 // Copyright 2014 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.tab;
 
 import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.app.Application;
 import android.content.Context;
@@ skipping 70 matching lines @@
 import org.chromium.chrome.browser.tabmodel.TabModel.TabLaunchType;
 import org.chromium.chrome.browser.tabmodel.TabModel.TabSelectionType;
 import org.chromium.chrome.browser.tabmodel.TabModelImpl;
 import org.chromium.chrome.browser.tabmodel.TabModelSelector;
 import org.chromium.chrome.browser.tabmodel.TabReparentingParams;
 import org.chromium.chrome.browser.util.ColorUtils;
 import org.chromium.chrome.browser.util.FeatureUtilities;
 import org.chromium.components.dom_distiller.core.DomDistillerUrlUtils;
 import org.chromium.components.navigation_interception.InterceptNavigationDelegate;
 import org.chromium.components.security_state.ConnectionSecurityLevel;
+import org.chromium.components.sync.SyncConstants;
 import org.chromium.content.browser.ChildProcessLauncher;
 import org.chromium.content.browser.ContentView;
 import org.chromium.content.browser.ContentViewClient;
 import org.chromium.content.browser.ContentViewCore;
 import org.chromium.content.browser.crypto.CipherFactory;
 import org.chromium.content_public.browser.GestureStateListener;
 import org.chromium.content_public.browser.LoadUrlParams;
 import org.chromium.content_public.browser.WebContents;
 import org.chromium.content_public.common.BrowserControlsState;
 import org.chromium.content_public.common.BrowserControlsState.BrowserControlsStateEnum;
@@ skipping 69 matching lines @@
     /** The current native page (e.g. chrome-native://newtab), or {@code null} if there is none. */
     private NativePage mNativePage;
 
     /** InfoBar container to show InfoBars for this tab. */
     private InfoBarContainer mInfoBarContainer;
 
     /** Controls overscroll pull-to-refresh behavior for this tab. */
     private SwipeRefreshHandler mSwipeRefreshHandler;
 
     /** The sync id of the Tab if session sync is enabled. */
-    private int mSyncId;
+    private int mSyncId = SyncConstants.INVALID_TAB_NODE_ID;
 
     /** {@link ContentViewCore} showing the current page, or {@code null} if the tab is frozen. */
     private ContentViewCore mContentViewCore;
 
     /** Listens to gesture events fired by the ContentViewCore. */
     private GestureStateListener mGestureStateListener;
 
     /** The parent view of the ContentView and the InfoBarContainer. */
     private View mContentView;
 
@@ skipping 2897 matching lines @@
     private native boolean nativeIsOfflinePage(long nativeTabAndroid);
     private native OfflinePageItem nativeGetOfflinePage(long nativeTabAndroid);
     private native void nativeSetInterceptNavigationDelegate(long nativeTabAndroid,
             InterceptNavigationDelegate delegate);
     private native void nativeAttachToTabContentManager(long nativeTabAndroid,
             TabContentManager tabContentManager);
     private native boolean nativeHasPrerenderedUrl(long nativeTabAndroid, String url);
     private native void nativeSetWebappManifestScope(long nativeTabAndroid, String scope);
     private native void nativeEnableEmbeddedMediaExperience(long nativeTabAndroid, boolean enabled);
 }