Have a recycler view to show search results.

-Have a recycler view layout for search widgets list.
-Make WidgetsFullSheet implement interface- SearchModeListener to get notified when user is using search and also when search results are ready.
-Have a WidgetsListSearchHeaderViewHolderBinder for search result headers which shows subtext in header as concatenated string of widget/shortcut labels.
-Modify WidgetsListAdapter and WidgetsDiffReporter to work well with search recycler view.

Test: Tested prototype locally. Also added robolectric test.
Bug: b/157286785
Change-Id: Ie29d9f295fddb6d727b5fc26a360f514f2f4a763

src/com/android/launcher3/widget/model/WidgetsListSearchHeaderEntry.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.launcher3.widget.model;
+
+import com.android.launcher3.model.WidgetItem;
+import com.android.launcher3.model.data.PackageItemInfo;
+import com.android.launcher3.widget.WidgetItemComparator;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+/** An information holder for an app which has widgets or/and shortcuts, to be shown in search. */
+public final class WidgetsListSearchHeaderEntry extends WidgetsListBaseEntry {
+
+    public final List<WidgetItem> mWidgets;
+
+    private boolean mIsWidgetListShown = false;
+    private boolean mHasEntryUpdated = false;
+
+    public WidgetsListSearchHeaderEntry(PackageItemInfo pkgItem, String titleSectionName,
+            List<WidgetItem> items) {
+        super(pkgItem, titleSectionName);
+        mWidgets = items.stream().sorted(new WidgetItemComparator()).collect(Collectors.toList());
+    }
+
+    /** Sets if the widgets list associated with this header is shown. */
+    public void setIsWidgetListShown(boolean isWidgetListShown) {
+        if (mIsWidgetListShown != isWidgetListShown) {
+            this.mIsWidgetListShown = isWidgetListShown;
+            mHasEntryUpdated = true;
+        } else {
+            mHasEntryUpdated = false;
+        }
+    }
+
+    /** Returns {@code true} if the widgets list associated with this header is shown. */
+    public boolean isWidgetListShown() {
+        return mIsWidgetListShown;
+    }
+
+    /** Returns {@code true} if this entry has been updated due to user interactions. */
+    public boolean hasEntryUpdated() {
+        return mHasEntryUpdated;
+    }
+
+    @Override
+    public String toString() {
+        return "SearchHeader:" + mPkgItem.packageName + ":" + mWidgets.size();
+    }
+
+    @Override
+    @Rank
+    public int getRank() {
+        return RANK_WIDGETS_LIST_SEARCH_HEADER;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof WidgetsListSearchHeaderEntry)) return false;
+        WidgetsListSearchHeaderEntry otherEntry = (WidgetsListSearchHeaderEntry) obj;
+        return mWidgets.equals(otherEntry.mWidgets) && mPkgItem.equals(otherEntry.mPkgItem)
+                && mTitleSectionName.equals(otherEntry.mTitleSectionName);
+    }
+}