Shortcut ctrl+shift+T added on android.

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelImpl.java

Index: chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelImpl.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelImpl.java b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelImpl.java
index 85f5a65bc85bf78cee4009a29482dec305e01974..7ea0a2630cc90a3f1d0be0cb5dceef25b4bbd5a8 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelImpl.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelImpl.java
@@ -9,6 +9,7 @@ import org.chromium.base.ObserverList;
 import org.chromium.base.TraceEvent;
 import org.chromium.chrome.browser.ChromeTabbedActivity;
 import org.chromium.chrome.browser.compositor.layouts.content.TabContentManager;
+import org.chromium.chrome.browser.ntp.RecentlyClosedBridge;
 import org.chromium.chrome.browser.partnercustomizations.HomepageManager;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tabmodel.TabCreatorManager.TabCreator;
@@ -45,6 +46,7 @@ public class TabModelImpl extends TabModelJniBridge {
     private final TabPersistentStore mTabSaver;
     private final TabModelDelegate mModelDelegate;
     private final ObserverList<TabModelObserver> mObservers;
+    private RecentlyClosedBridge mRecentlyClosedBridge;
 
     // Undo State Tracking -------------------------------------------------------------------------
 
@@ -81,6 +83,7 @@ public class TabModelImpl extends TabModelJniBridge {
         mModelDelegate = modelDelegate;
         mIsUndoSupported = supportUndo;
         mObservers = new ObserverList<TabModelObserver>();
+        mRecentlyClosedBridge = new RecentlyClosedBridge(getProfile());
     }
 
     @Override
@@ -99,7 +102,7 @@ public class TabModelImpl extends TabModelJniBridge {
         mRewoundList.destroy();
         mTabs.clear();
         mObservers.clear();
-
+        mRecentlyClosedBridge.destroy();
         super.destroy();
     }
 
@@ -720,8 +723,11 @@ public class TabModelImpl extends TabModelJniBridge {
     @Override
     protected boolean createTabWithWebContents(Tab parent, boolean incognito,
             WebContents webContents, int parentId) {
+        // TODO(xingliu): figure out if TabLaunchType.FROM_LONGPRESS_FOREGROUND affects

[Theresa, 2016/07/07 19:00:13]

We need to figure this out before the CL lands. I pinged UX, will try to get a
decision around this resolved soon.

[xingliu, 2016/07/08 21:26:48]

change it back to background, and add code to fix 'the only tab' problem. So it
don't modify current UI behavior.

+        // other features. FROM_LONGPRESS_FOREGROUND makes tab restored in foreground when called
+        // from native code.
         return getTabCreator(incognito).createTabWithWebContents(parent, webContents, parentId,
-                TabLaunchType.FROM_LONGPRESS_BACKGROUND);
+                TabLaunchType.FROM_LONGPRESS_FOREGROUND);
     }
 
     @Override
@@ -738,4 +744,19 @@ public class TabModelImpl extends TabModelJniBridge {
     protected boolean isSessionRestoreInProgress() {
         return mModelDelegate.isSessionRestoreInProgress();
     }
+
+    @Override
+    public void openMostRecentlyClosedTab() {
+        // First try to recover tab from rewound list, same as {@link UndoBarController}.
+        if (mRewoundList.hasPendingClosures()) {
+            Tab tab = mRewoundList.getNextRewindableTab();
+            if (tab == null) return;
+            cancelTabClosure(tab.getId());
+            return;
+        }
+
+        // If there are no pending closures in the rewound list,
+        // then try to restore the tab from the native tab restore service.
+        mRecentlyClosedBridge.openRecentlyClosedTab();

[Theresa, 2016/07/07 19:00:12]

Should we record any UMA for this? Maybe just a user action, e.g.
AndroidTabCloseUndo.FromKeyboard or something like that?

We currently record a histogram for undoing via the snackbar in
UndoBarController.java

[xingliu, 2016/07/08 21:26:47]

Done in ChromeTabbedActivity.onMenuOrKeyboardAction()

+    }
 }