Update WebAPK after the user closes WebAPK

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkUpdateTask.java

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkUpdateTask.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkUpdateTask.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkUpdateTask.java
new file mode 100644
index 0000000000000000000000000000000000000000..ed84aca2f9fb680e00fd18ac21d619638ba135a0
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+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkUpdateTask.java
@@ -0,0 +1,130 @@
+// 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.webapps;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.pm.PackageManager;
+import android.os.StrictMode;
+
+import org.chromium.base.ApplicationStatus;
+import org.chromium.base.ContextUtils;
+import org.chromium.chrome.browser.background_task_scheduler.NativeBackgroundTask;
+import org.chromium.chrome.browser.banners.InstallerDelegate;
+import org.chromium.components.background_task_scheduler.BackgroundTask.TaskFinishedCallback;
+import org.chromium.components.background_task_scheduler.TaskIds;
+import org.chromium.components.background_task_scheduler.TaskParameters;
+
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Handles servicing of background WebAPK update requests coming via background_task_scheduler

[Xi Han, 2017/09/11 15:24:23]

It is worthy mentioning that: the scheduled task will update all WebAPKs that
are out-of-date. It is possible that multiple background tasks are created when
there are multiple webapks are launched and need to be updated, and it is fine
since the background tasks will be executed one by one.

+ * component.
+ */
+public class WebApkUpdateTask extends NativeBackgroundTask {
+    /** Whether the task was stopped. */
+    private boolean mStopped = false;
+
+    /** The WebappDataStorage for the WebAPK to update. */
+    private WebappDataStorage mStorageToUpdate = null;
+
+    @Override
+    @StartBeforeNativeResult
+    protected int onStartTaskBeforeNativeLoaded(
+            Context context, TaskParameters taskParameters, TaskFinishedCallback callback) {
+        assert taskParameters.getTaskId() == TaskIds.WEBAPK_UPDATE_JOB_ID;
+
+        StrictMode.ThreadPolicy oldPolicy = StrictMode.allowThreadDiskReads();
+        try {
+            WebappRegistry.warmUpSharedPrefs();
+        } finally {
+            StrictMode.setThreadPolicy(oldPolicy);
+        }
+
+        ArrayList<String> ids = findInstalledWebApksWithPendingUpdate();
+        for (String id : ids) {
+            WebappDataStorage storage = WebappRegistry.getInstance().getWebappDataStorage(id);
+            if (!isWebApkActivityRunning(storage.getWebApkPackageName())) {
+                mStorageToUpdate = storage;
+                return LOAD_NATIVE;
+            }
+        }
+        return ids.isEmpty() ? DONE : RESCHEDULE;
+    }
+
+    @Override
+    protected void onStartTaskWithNative(
+            Context context, TaskParameters taskParameters, final TaskFinishedCallback callback) {
+        assert taskParameters.getTaskId() == TaskIds.WEBAPK_UPDATE_JOB_ID;
+
+        WebApkUpdateManager updateManager = new WebApkUpdateManager(mStorageToUpdate);
+        Runnable nextUpdateRunner = new Runnable() {
+            @Override
+            public void run() {
+                boolean moreToUpdate = !findInstalledWebApksWithPendingUpdate().isEmpty();
+                callback.taskFinished(!mStopped && moreToUpdate);
+            }
+        };
+        updateManager.updateNow(nextUpdateRunner);
+    }
+
+    @Override
+    protected boolean onStopTaskBeforeNativeLoaded(Context context, TaskParameters taskParameters) {
+        assert taskParameters.getTaskId() == TaskIds.WEBAPK_UPDATE_JOB_ID;
+
+        // Native didn't complete loading, but it was supposed to. Presume that we need to
+        // reschedule.
+        return true;
+    }
+
+    @Override
+    protected boolean onStopTaskWithNative(Context context, TaskParameters taskParameters) {
+        assert taskParameters.getTaskId() == TaskIds.WEBAPK_UPDATE_JOB_ID;
+
+        mStopped = true;
+        // Updating a single WebAPK is a fire and forget task. However, there might be several
+        // WebAPKs that we need to update.
+        return true;
+    }
+
+    @Override
+    public void reschedule(Context context) {}
+
+    /** Returns whether a WebApkActivity with {@link webApkPackageName} is running. */
+    private static boolean isWebApkActivityRunning(String webApkPackageName) {
+        for (WeakReference<Activity> activity : ApplicationStatus.getRunningActivities()) {
+            if (!(activity.get() instanceof WebApkActivity)) {
+                continue;
+            }
+            WebApkActivity webApkActivity = (WebApkActivity) activity.get();
+            if (webApkPackageName.equals(webApkActivity.getWebApkPackageName())) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Returns list of WebAPKs which have pending updates. Filters out WebAPKs which have been
+     * uninstalled.
+     */
+    private ArrayList<String> findInstalledWebApksWithPendingUpdate() {
+        List<String> ids = WebappRegistry.getInstance().findWebApksWithPendingUpdate();
+        // Filter out WebAPKs which have been uninstalled. A user may have uninstalled a WebAPK
+        // between the time that the update was requested and the time that BackgroundTaskScheduler
+        // runs the update task.
+        ArrayList<String> installedIds = new ArrayList<String>();
+        PackageManager packageManager = ContextUtils.getApplicationContext().getPackageManager();
+        for (String id : ids) {
+            WebappDataStorage storage = WebappRegistry.getInstance().getWebappDataStorage(id);
+            if (InstallerDelegate.isInstalled(packageManager, storage.getWebApkPackageName())) {
+                installedIds.add(id);
+            }
+        }
+        return installedIds;
+    }
+}