Refactor SearchAlgorithm and SearchCallback interface to work on generic search result type.

Test: Manually tested that 'All apps' search works fine
Bug: b/157286785
Change-Id: Id4b7fb133149e9211f871b46b47d5853ec0e0050

src/com/android/launcher3/search/SearchAlgorithm.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2017 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.search;
+
+/**
+ * An interface for handling search.
+ *
+ * @param <T> Search Result type
+ */
+public interface SearchAlgorithm<T> {
+
+    /**
+     * Performs search and sends the result to {@link SearchCallback}.
+     */
+    void doSearch(String query, SearchCallback<T> callback);
+
+    /**
+     * Cancels any active request.
+     */
+    void cancel(boolean interruptActiveRequests);
+}