Add a deletion helper view for clearing space.

This view provides an interface which allows users to clear out
apps and other data which they may no longer need to alleviate
storage pressure. This implementation gives the bits to uninstall
apps which have not been used within the last 60 days from the
system.

A future patch will add in the ability to extend the deletion helper
view to have additional clearing types.

Change-Id: I65cba54ca247d52227e67e2fa9b84fe63fb8ab34
(cherry picked from commit a671272bf6)

src/com/android/settings/deletionhelper/AppStateUsageStatsBridge.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2016 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.settings.deletionhelper;
+
+import android.app.usage.UsageStats;
+import android.app.usage.UsageStatsManager;
+import android.content.Context;
+import android.content.pm.ApplicationInfo;
+
+import com.android.settings.applications.AppStateBaseBridge;
+import com.android.settingslib.applications.ApplicationsState;
+import com.android.settingslib.applications.ApplicationsState.AppEntry;
+import com.android.settingslib.applications.ApplicationsState.AppFilter;
+
+import java.util.ArrayList;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Connects data from the UsageStatsManager to the ApplicationsState.
+ */
+public class AppStateUsageStatsBridge extends AppStateBaseBridge {
+    private UsageStatsManager mUsageStatsManager;
+    public static final long NEVER_USED = -1;
+    public static final long UNKNOWN_LAST_USE = -2;
+
+    public AppStateUsageStatsBridge(Context context, ApplicationsState appState,
+                                    Callback callback) {
+        super(appState, callback);
+        mUsageStatsManager =
+                (UsageStatsManager) context.getSystemService(Context.USAGE_STATS_SERVICE);
+    }
+
+    @Override
+    protected void loadAllExtraInfo() {
+        ArrayList<AppEntry> apps = mAppSession.getAllApps();
+        if (apps == null) return;
+
+        final Map<String, UsageStats> map = mUsageStatsManager.queryAndAggregateUsageStats(0,
+                System.currentTimeMillis());
+        for (AppEntry entry : apps) {
+            UsageStats usageStats = map.get(entry.info.packageName);
+            entry.extraInfo = getDaysSinceLastUse(usageStats);
+        }
+    }
+
+    @Override
+    protected void updateExtraInfo(AppEntry app, String pkg, int uid) {
+        Map<String, UsageStats> map = mUsageStatsManager.queryAndAggregateUsageStats(0,
+                System.currentTimeMillis());
+        UsageStats usageStats = map.get(app.info.packageName);
+        app.extraInfo = getDaysSinceLastUse(usageStats);
+    }
+
+    private long getDaysSinceLastUse(UsageStats stats) {
+        if (stats == null) {
+            return NEVER_USED;
+        }
+        long lastUsed = stats.getLastTimeUsed();
+        // Sometimes, a usage is recorded without a time and we don't know when the use was.
+        if (lastUsed == 0) {
+            return UNKNOWN_LAST_USE;
+        }
+        return TimeUnit.MILLISECONDS.toDays(System.currentTimeMillis() - lastUsed);
+
+    }
+
+    /**
+     * Filters only non-system apps which haven't been used in the last 60 days. If an app's last
+     * usage is unknown, it is skipped.
+     */
+    public static final AppFilter FILTER_USAGE_STATS = new AppFilter() {
+        private long UNUSED_DAYS_DELETION_THRESHOLD = 60;
+
+        @Override
+        public void init() {
+        }
+
+        @Override
+        public boolean filterApp(AppEntry info) {
+            if (info == null) return false;
+            boolean isBundled = (info.info.flags & ApplicationInfo.FLAG_SYSTEM) != 0;
+            return isExtraInfoValid(info.extraInfo) && !isBundled;
+        }
+
+        private boolean isExtraInfoValid(Object extraInfo) {
+            if (extraInfo == null || !(extraInfo instanceof Long)) {
+                return false;
+            }
+
+            long daysSinceLastUse = (long) extraInfo;
+            return daysSinceLastUse >= UNUSED_DAYS_DELETION_THRESHOLD ||
+                    daysSinceLastUse == NEVER_USED;
+        }
+    };
+}