🍝🏠 Refactor MostVisited UI management, extract it for reuse in Home.

chrome/android/java/src/org/chromium/chrome/browser/suggestions/TileGrid.java

+// Copyright 2017 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.suggestions;
+
+import android.view.LayoutInflater;
+import android.view.ViewGroup;
+
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.ntp.ContextMenuManager;
+import org.chromium.chrome.browser.ntp.MostVisitedLayout;
+import org.chromium.chrome.browser.ntp.cards.ItemViewType;
+import org.chromium.chrome.browser.ntp.cards.Leaf;
+import org.chromium.chrome.browser.ntp.cards.NewTabPageViewHolder;
+import org.chromium.chrome.browser.ntp.cards.NewTabPageViewHolder.PartialBindCallback;
+
+/**
+ * The model and controller for a group of site suggestion tiles that will be rendered in a grid.
+ */
+public class TileGrid extends Leaf implements TileGroup.Observer {

[dgn, 2017/01/31 18:21:35]

what if the user removes all the tiles? do we still leave the grid in? Shouldn't
that be an optionalleaf instead?

[Michael van Ouwerkerk, 2017/02/03 12:37:48]

It was rendering with 0 height so the user wouldn't know, but with OptionalLeaf
it's cleaner. Done.

+    private static final int MAX_TILES = 4;
+    private static final int MAX_ROWS = 1;
+
+    private final TileGroup mTileGroup;
+
+    public TileGrid(SuggestionsUiDelegate uiDelegate, ContextMenuManager contextMenuManager,
+            TileGroup.Delegate tileGroupDelegate) {
+        mTileGroup = new TileGroup(
+                uiDelegate, contextMenuManager, tileGroupDelegate, /* observer = */ this);
+        mTileGroup.startObserving(MAX_TILES);
+    }
+
+    @Override
+    @ItemViewType
+    protected int getItemViewType() {
+        return ItemViewType.TILE_GRID;
+    }
+
+    @Override
+    protected void onBindViewHolder(NewTabPageViewHolder holder) {
+        assert holder instanceof ViewHolder;
+        ((ViewHolder) holder).onBindViewHolder(mTileGroup);
+    }
+
+    @Override
+    public void onInitialTileDataLoaded() {
+        notifyItemChanged(0);
+    }
+
+    @Override
+    public void onTileDataChanged() {
+        notifyItemChanged(0);
+    }
+
+    @Override
+    public void onTileCountChanged() {}

[dgn, 2017/01/31 18:21:35]

why no notification here?

[Michael van Ouwerkerk, 2017/02/03 12:37:48]

Done.

+
+    @Override
+    public void onTileIconChanged(final Tile tile) {
+        notifyItemChanged(0, new PartialBindCallback() {
+            @Override
+            public void onResult(NewTabPageViewHolder holder) {
+                assert holder instanceof ViewHolder;
+                ((ViewHolder) holder).updateIconView(tile);
+            }
+        });
+    }
+
+    @Override
+    public void onLoadTaskAdded() {}
+
+    @Override
+    public void onLoadTaskCompleted() {}
+
+    /**
+     * The {@code ViewHolder} for the {@link TileGrid}.
+     */
+    public static class ViewHolder extends NewTabPageViewHolder {
+        private final MostVisitedLayout mLayout;
+
+        public ViewHolder(ViewGroup parentView) {
+            super(LayoutInflater.from(parentView.getContext())
+                            .inflate(R.layout.suggestions_site_tile_grid, parentView, false));
+            mLayout = (MostVisitedLayout) itemView;
+        }
+
+        public void onBindViewHolder(TileGroup tileGroup) {
+            mLayout.setMaxRows(MAX_ROWS);
+            tileGroup.renderTileViews(mLayout, /* trackLoadTasks = */ false);
+        }
+
+        public void updateIconView(Tile tile) {
+            mLayout.updateIconView(tile.getUrl(), tile.getIcon());
+        }
+    }
+}