Provide a recommended next tab when closing tab

Bug: 951436
Change-Id: I88aaa98ddb82103eea0920adc830bdbe6f06e551
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1564351Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#650643}

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabListMediator.java

@@ -304,6 +304,8 @@ class TabListMediator {
 
         mTabModelSelector.getTabModelFilterProvider().addTabModelFilterObserver(mTabModelObserver);
 
+        // TODO(meiliang): follow up with unit tests to test the close signal is sent correctly with
+        // the recommendedNextTab.
         mTabClosedListener = new TabActionListener() {
             @Override
             public void run(int tabId) {
@@ -318,9 +320,32 @@ class TabListMediator {
                     }
                 }
                 onTabClosedFrom(tabId, mComponentName);
+
+                Tab currentTab = mTabModelSelector.getCurrentTab();
+                Tab closingTab =
+                        TabModelUtils.getTabById(mTabModelSelector.getCurrentModel(), tabId);
+                Tab nextTab = currentTab == closingTab ? getNextTab(tabId) : null;
+
                 mTabModelSelector.getCurrentModel().closeTab(
-                        TabModelUtils.getTabById(mTabModelSelector.getCurrentModel(), tabId), false,
-                        false, true);
+                        closingTab, nextTab, false, false, true);
+            }
+
+            private Tab getNextTab(int closingTabId) {
+                int closingTabIndex = mModel.indexFromId(closingTabId);
+
+                if (closingTabIndex == TabModel.INVALID_TAB_INDEX) {
+                    assert false;
+                    return null;
+                }
+
+                int nextTabId = Tab.INVALID_TAB_ID;
+                if (mModel.size() > 1) {
+                    nextTabId = closingTabIndex == 0
+                            ? mModel.get(closingTabIndex + 1).get(TabProperties.TAB_ID)
+                            : mModel.get(closingTabIndex - 1).get(TabProperties.TAB_ID);
+                }
+
+                return TabModelUtils.getTabById(mTabModelSelector.getCurrentModel(), nextTabId);
             }
         };
     }

chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/TabListMediatorUnitTest.java

@@ -184,7 +184,7 @@ public class TabListMediatorUnitTest {
                 .get(TabProperties.TAB_CLOSED_LISTENER)
                 .run(mModel.get(1).get(TabProperties.TAB_ID));
 
-        verify(mTabModel).closeTab(eq(mTab2), eq(false), eq(false), eq(true));
+        verify(mTabModel).closeTab(eq(mTab2), eq(null), eq(false), eq(false), eq(true));
     }
 
     @Test

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

@@ -110,6 +110,12 @@ public class EmptyTabModel implements TabModel {
         return false;
     }
 
+    @Override
+    public boolean closeTab(
+            Tab tab, Tab recommendedNextTab, boolean animate, boolean uponExit, boolean canUndo) {
+        return closeTab(tab, animate, uponExit, canUndo);
+    }
+
     @Override
     public TabList getComprehensiveModel() {
         return this;

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

@@ -131,6 +131,15 @@ public class IncognitoTabModel implements TabModel {
         return retVal;
     }
 
+    @Override
+    public boolean closeTab(
+            Tab tab, Tab recommendedNextTab, boolean animate, boolean uponExit, boolean canUndo) {
+        boolean retVal =
+                mDelegateModel.closeTab(tab, recommendedNextTab, animate, uponExit, canUndo);
+        destroyIncognitoIfNecessary();
+        return retVal;
+    }
+
     @Override
     public Tab getNextTabIfClosed(int id) {
         return mDelegateModel.getNextTabIfClosed(id);

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

@@ -99,6 +99,12 @@ public class SingleTabModel implements TabModel {
         return false;
     }
 
+    @Override
+    public boolean closeTab(
+            Tab tab, Tab recommendedNextTab, boolean animate, boolean uponExit, boolean canUndo) {
+        return closeTab(tab, animate, uponExit, canUndo);
+    }
+
     /**
      * In webapps, calls finish on the activity, but keeps it in recents. In Document mode,
      * finishes and removes from recents. We use mBlockNewWindows flag to distinguish the user

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

@@ -4,6 +4,8 @@
 
 package org.chromium.chrome.browser.tabmodel;
 
+import android.support.annotation.Nullable;
+
 import org.chromium.chrome.browser.profiles.Profile;
 import org.chromium.chrome.browser.tab.Tab;
 
@@ -44,6 +46,28 @@ public interface TabModel extends TabList {
      */
     public boolean closeTab(Tab tab, boolean animate, boolean uponExit, boolean canUndo);
 
+    /**
+     * Unregisters and destroys the specified tab, and then switches to {@code recommendedNextTab}
+     * if it is not null, otherwise switches to the previous tab.
+     *
+     * @param tab The non-null tab to close.
+     * @param recommendedNextTab The tab to switch to if not null.
+     * @param animate true iff the closing animation should be displayed.
+     * @param uponExit true iff the tab is being closed upon application exit (after user presses
+     *                 the system back button).
+     * @param canUndo Whether or not this action can be undone. If this is {@code true} and
+     *                {@link #supportsPendingClosures()} is {@code true}, this {@link Tab}
+     *                will not actually be closed until {@link #commitTabClosure(int)} or
+     *                {@link #commitAllTabClosures()} is called, but it will be effectively removed
+     *                from this list. To get a comprehensive list of all tabs, including ones that
+     *                have been partially closed, use the {@link TabList} from
+     *                {@link #getComprehensiveModel()}.
+     *
+     * @return true if the tab was found.
+     */
+    public boolean closeTab(Tab tab, @Nullable Tab recommendedNextTab, boolean animate,
+            boolean uponExit, boolean canUndo);
+
     /**
      * Returns which tab would be selected if the specified tab {@code id} were closed.
      * @param id The ID of tab which would be closed.

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

@@ -95,7 +95,7 @@ public class TabModelImpl extends TabModelJniBridge {
 
     @Override
     public void removeTab(Tab tab) {
-        removeTabAndSelectNext(tab, TabSelectionType.FROM_CLOSE, false, true);
+        removeTabAndSelectNext(tab, null, TabSelectionType.FROM_CLOSE, false, true);
 
         for (TabModelObserver obs : mObservers) obs.tabRemoved(tab);
     }
@@ -348,7 +348,13 @@ public class TabModelImpl extends TabModelJniBridge {
 
     @Override
     public boolean closeTab(Tab tabToClose, boolean animate, boolean uponExit, boolean canUndo) {
-        return closeTab(tabToClose, animate, uponExit, canUndo, canUndo);
+        return closeTab(tabToClose, null, animate, uponExit, canUndo, canUndo);
+    }
+
+    @Override
+    public boolean closeTab(
+            Tab tab, Tab recommendedNextTab, boolean animate, boolean uponExit, boolean canUndo) {
+        return closeTab(tab, recommendedNextTab, animate, uponExit, canUndo, canUndo);
     }
 
     /**
@@ -359,8 +365,8 @@ public class TabModelImpl extends TabModelJniBridge {
      *               closure. Observers will still be notified of a committed/cancelled closure
      *               even if they are not notified of a pending closure to start with.
      */
-    private boolean closeTab(Tab tabToClose, boolean animate, boolean uponExit,
-            boolean canUndo, boolean notify) {
+    private boolean closeTab(Tab tabToClose, Tab recommendedNextTab, boolean animate,
+            boolean uponExit, boolean canUndo, boolean notify) {
         if (tabToClose == null) {
             assert false : "Tab is null!";
             return false;
@@ -373,7 +379,7 @@ public class TabModelImpl extends TabModelJniBridge {
 
         canUndo &= supportsPendingClosures();
 
-        startTabClosure(tabToClose, animate, uponExit, canUndo);
+        startTabClosure(tabToClose, recommendedNextTab, animate, uponExit, canUndo);
         if (notify && canUndo) {
             for (TabModelObserver obs : mObservers) obs.tabPendingClosure(tabToClose);
         }
@@ -390,7 +396,7 @@ public class TabModelImpl extends TabModelJniBridge {
                 continue;
             }
             tab.setClosing(true);
-            closeTab(tab, false, false, canUndo, false);
+            closeTab(tab, null, false, false, canUndo, false);
         }
         if (canUndo && supportsPendingClosures()) {
             for (TabModelObserver obs : mObservers) obs.multipleTabsPendingClosure(tabs, false);
@@ -452,7 +458,7 @@ public class TabModelImpl extends TabModelJniBridge {
         while (getCount() > 0) {
             Tab tab = getTabAt(0);
             closedTabs.add(tab);
-            closeTab(tab, animate, uponExit, canUndo, false);
+            closeTab(tab, null, animate, uponExit, canUndo, false);
         }
 
         if (!uponExit && canUndo && supportsPendingClosures()) {
@@ -548,7 +554,8 @@ public class TabModelImpl extends TabModelJniBridge {
      *                {@link #commitTabClosure(int)} or {@link #commitAllTabClosures()} needs to be
      *                called to actually delete and clean up {@code tab}.
      */
-    private void startTabClosure(Tab tab, boolean animate, boolean uponExit, boolean canUndo) {
+    private void startTabClosure(
+            Tab tab, Tab recommendedNextTab, boolean animate, boolean uponExit, boolean canUndo) {
         tab.setClosing(true);
 
         for (TabModelObserver obs : mObservers) obs.willCloseTab(tab, animate);
@@ -557,14 +564,15 @@ public class TabModelImpl extends TabModelJniBridge {
         int selectionType = uponExit ? TabSelectionType.FROM_EXIT : TabSelectionType.FROM_CLOSE;
         boolean pauseMedia = canUndo;
         boolean updateRewoundList = !canUndo;
-        removeTabAndSelectNext(tab, selectionType, pauseMedia, updateRewoundList);
+        removeTabAndSelectNext(
+                tab, recommendedNextTab, selectionType, pauseMedia, updateRewoundList);
     }
 
     /**
      * Removes the given tab from the tab model and selects a new tab.
      */
-    private void removeTabAndSelectNext(Tab tab, @TabSelectionType int selectionType,
-            boolean pauseMedia, boolean updateRewoundList) {
+    private void removeTabAndSelectNext(Tab tab, Tab recommendedNextTab,
+            @TabSelectionType int selectionType, boolean pauseMedia, boolean updateRewoundList) {
         assert selectionType == TabSelectionType.FROM_CLOSE
                 || selectionType == TabSelectionType.FROM_EXIT;
 
@@ -573,7 +581,8 @@ public class TabModelImpl extends TabModelJniBridge {
 
         Tab currentTabInModel = TabModelUtils.getCurrentTab(this);
         Tab adjacentTabInModel = getTabAt(closingTabIndex == 0 ? 1 : closingTabIndex - 1);
-        Tab nextTab = getNextTabIfClosed(closingTabId);
+        Tab nextTab =
+                recommendedNextTab == null ? getNextTabIfClosed(closingTabId) : recommendedNextTab;
 
         // TODO(dtrainor): Update the list of undoable tabs instead of committing it.
         if (updateRewoundList) commitAllTabClosures();

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/document/DocumentTabModelImpl.java

@@ -265,6 +265,12 @@ public class DocumentTabModelImpl extends TabModelJniBridge implements DocumentT
         return false;
     }
 
+    @Override
+    public boolean closeTab(
+            Tab tab, Tab recommendedNextTab, boolean animate, boolean uponExit, boolean canUndo) {
+        return closeTab(tab, animate, uponExit, canUndo);
+    }
+
     @Override
     protected TabDelegate getTabCreator(boolean incognito) {
         return null;

chrome/android/javatests/src/org/chromium/chrome/browser/tabmodel/document/MockDocumentTabModel.java

@@ -43,6 +43,12 @@ public class MockDocumentTabModel implements DocumentTabModel {
         return false;
     }
 
+    @Override
+    public boolean closeTab(
+            Tab tab, Tab recommendedNextTab, boolean animate, boolean uponExit, boolean canUndo) {
+        return closeTab(tab, animate, uponExit, canUndo);
+    }
+
     @Override
     public Tab getNextTabIfClosed(int id) {
         Assert.fail();