Show correct number of columns for tab grid as orientation changes

Add ComponentCallbacks in TabListMediator to listen to
orientation changes and change span count of GridLayoutManager
accordingly.

TODO:
* Fix the problem of landscape Thumbnail showing incorrectly in
portrait mode.
* Dynamically set span count base on screen width, min width of cards
and paddings.

Bug: 945740
Change-Id: I961274492e35c097e6440caeaff78ae7cd7d83db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1559238Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Commit-Queue: Yue Zhang <yuezhanggg@google.com>
Cr-Commit-Position: refs/heads/master@{#649319}

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

@@ -43,7 +43,8 @@ public class TabListCoordinator implements Destroyable {
         int NUM_ENTRIES = 2;
     }
 
-    private static final int GRID_LAYOUT_SPAN_COUNT = 2;
+    static final int GRID_LAYOUT_SPAN_COUNT_PORTRAIT = 2;
+    static final int GRID_LAYOUT_SPAN_COUNT_LANDSCAPE = 3;
     private final SimpleRecyclerViewMcpBase mModelChangeProcessor;
     private final TabListMediator mMediator;
     private final TabListRecyclerView mRecyclerView;
@@ -103,7 +104,8 @@ public class TabListCoordinator implements Destroyable {
         mRecyclerView.setAdapter(adapter);
 
         if (mMode == TabListMode.GRID) {
-            mRecyclerView.setLayoutManager(new GridLayoutManager(context, GRID_LAYOUT_SPAN_COUNT));
+            mRecyclerView.setLayoutManager(
+                    new GridLayoutManager(context, GRID_LAYOUT_SPAN_COUNT_PORTRAIT));
         } else if (mMode == TabListMode.STRIP) {
             mRecyclerView.setLayoutManager(
                     new LinearLayoutManager(context, LinearLayoutManager.HORIZONTAL, false));
@@ -122,6 +124,8 @@ public class TabListCoordinator implements Destroyable {
             ItemTouchHelper touchHelper = new ItemTouchHelper(mMediator.getItemTouchHelperCallback(
                     context.getResources().getDimension(R.dimen.swipe_to_dismiss_threshold)));
             touchHelper.attachToRecyclerView(mRecyclerView);
+            mMediator.registerOrientationListener(
+                    (GridLayoutManager) mRecyclerView.getLayoutManager());
         }
     }
 

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

@@ -4,17 +4,21 @@
 
 package org.chromium.chrome.browser.tasks.tab_management;
 
+import android.content.ComponentCallbacks;
+import android.content.res.Configuration;
 import android.graphics.Bitmap;
 import android.graphics.Canvas;
 import android.graphics.drawable.Drawable;
 import android.os.Handler;
 import android.support.annotation.IntDef;
 import android.support.annotation.Nullable;
+import android.support.v7.widget.GridLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.helper.ItemTouchHelper;
 import android.view.View;
 
 import org.chromium.base.Callback;
+import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.metrics.RecordUserAction;
@@ -139,6 +143,7 @@ class TabListMediator {
     private final CreateGroupButtonProvider mCreateGroupButtonProvider;
     private final String mComponentName;
     private boolean mCloseAllRelatedTabs;
+    private ComponentCallbacks mComponentCallbacks;
 
     private final TabActionListener mTabSelectedListener = new TabActionListener() {
         @Override
@@ -426,6 +431,23 @@ class TabListMediator {
         };
     }
 
+    void registerOrientationListener(GridLayoutManager manager) {
+        // TODO(yuezhanggg): Try to dynamically determine span counts based on screen width,
+        // minimum card width and padding.
+        mComponentCallbacks = new ComponentCallbacks() {
+            @Override
+            public void onConfigurationChanged(Configuration newConfig) {
+                manager.setSpanCount(newConfig.orientation == Configuration.ORIENTATION_PORTRAIT
+                                ? TabListCoordinator.GRID_LAYOUT_SPAN_COUNT_PORTRAIT
+                                : TabListCoordinator.GRID_LAYOUT_SPAN_COUNT_LANDSCAPE);
+            }
+
+            @Override
+            public void onLowMemory() {}
+        };
+        ContextUtils.getApplicationContext().registerComponentCallbacks(mComponentCallbacks);
+    }
+
     /**
      * Destroy any members that needs clean up.
      */
@@ -440,6 +462,9 @@ class TabListMediator {
             mTabModelSelector.getTabModelFilterProvider().removeTabModelFilterObserver(
                     mTabModelObserver);
         }
+        if (mComponentCallbacks != null) {
+            ContextUtils.getApplicationContext().unregisterComponentCallbacks(mComponentCallbacks);
+        }
     }
 
     private void addTabInfoToModel(final Tab tab, int index, boolean isSelected) {