[Offline Prefetch] Create a new JobScheduler task to wake up for net activity.

chrome/android/java/src/org/chromium/chrome/browser/offlinepages/prefetch/PrefetchBackgroundTask.java

Index: chrome/android/java/src/org/chromium/chrome/browser/offlinepages/prefetch/PrefetchBackgroundTask.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/prefetch/PrefetchBackgroundTask.java b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/prefetch/PrefetchBackgroundTask.java
new file mode 100644
index 0000000000000000000000000000000000000000..16219c186ec7ee526cecc45b0880d2bf1d78b46e
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/prefetch/PrefetchBackgroundTask.java
@@ -0,0 +1,164 @@
+// 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.offlinepages.prefetch;
+
+import android.content.Context;
+
+import org.chromium.base.ContextUtils;
+import org.chromium.base.Log;
+import org.chromium.base.VisibleForTesting;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.annotations.SuppressFBWarnings;
+import org.chromium.base.library_loader.LibraryProcessType;
+import org.chromium.base.library_loader.ProcessInitException;
+import org.chromium.chrome.browser.init.ChromeBrowserInitializer;
+import org.chromium.chrome.browser.profiles.Profile;
+import org.chromium.components.background_task_scheduler.BackgroundTask;
+import org.chromium.components.background_task_scheduler.BackgroundTask.TaskFinishedCallback;
+import org.chromium.components.background_task_scheduler.BackgroundTaskScheduler;
+import org.chromium.components.background_task_scheduler.BackgroundTaskSchedulerFactory;
+import org.chromium.components.background_task_scheduler.TaskIds;
+import org.chromium.components.background_task_scheduler.TaskInfo;
+import org.chromium.components.background_task_scheduler.TaskParameters;
+import org.chromium.content.browser.BrowserStartupController;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Handles servicing background offlining requests.
+ *
+ * Can schedule or cancel tasks, and handles the actual initialization that
+ * happens when a task fires.
+ */
+@JNINamespace("offline_pages::prefetch")
+public class PrefetchBackgroundTask implements BackgroundTask {
+    private static final String TAG = "OPPrefetchBGTask";
+
+    private long mNativeTask = 0;
+    private TaskFinishedCallback mTaskFinishedCallback = null;
+
+    private Profile mProfile;
+
+    public PrefetchBackgroundTask() {
+        mProfile = Profile.getLastUsedProfile();
+    }
+
+    public PrefetchBackgroundTask(Profile profile) {
+        mProfile = profile;
+    }
+
+    /**
+     * Schedules the default 'NWake' task for the prefetching service.
+     *
+     * This task will only be scheduled on a good network type.
+     * TODO(dewittj): Handle skipping work if the battery percentage is too low.
+     */
+    @CalledByNative
+    public static void scheduleTask() {
+        BackgroundTaskScheduler scheduler = BackgroundTaskSchedulerFactory.getScheduler();
+        TaskInfo taskInfo =
+                TaskInfo.createOneOffTask(TaskIds.OFFLINE_PAGES_PREFETCH_JOB_ID,

[Dmitry Titov, 2017/05/02 23:51:42]

This is where we would change it to be a repeating task, correct? Do you plan to
change it in a later CL?

[dewittj, 2017/05/03 15:45:40]

Yes, in another patch.

+                                PrefetchBackgroundTask.class,
+                                // Minimum time to wait
+                                TimeUnit.MINUTES.toMillis(15),
+                                // Maximum time to wait.  After this interval the event will fire
+                                // regardless of whether the conditions are right.
+                                TimeUnit.DAYS.toMillis(7))
+                        .setRequiredNetworkType(TaskInfo.NETWORK_TYPE_UNMETERED)
+                        .setIsPersisted(true)
+                        .setUpdateCurrent(true)
+                        .build();
+        scheduler.schedule(ContextUtils.getApplicationContext(), taskInfo);
+    }
+
+    /**
+     * Cancels the default 'NWake' task for the prefetching service.
+     */
+    @CalledByNative
+    public static void cancelTask() {
+        BackgroundTaskScheduler scheduler = BackgroundTaskSchedulerFactory.getScheduler();
+        scheduler.cancel(
+                ContextUtils.getApplicationContext(), TaskIds.OFFLINE_PAGES_PREFETCH_JOB_ID);
+    }
+
+    /**
+     * Initializer that runs when the task wakes up Chrome.
+     *
+     * Loads the native library and then calls into the PrefetchService, which then manages the
+     * lifetime of this task.
+     */
+    @Override
+    public boolean onStartTask(
+            Context context, TaskParameters taskParameters, TaskFinishedCallback callback) {
+        assert taskParameters.getTaskId() == TaskIds.OFFLINE_PAGES_PREFETCH_JOB_ID;
+        if (mNativeTask != 0) return false;
+
+        // TODO(dewittj): Ensure that the conditions are right to do work.  If the maximum time to
+        // wait is reached, it is possible the task will fire even if network conditions are
+        // incorrect.
+
+        // Ensures that native potion of the browser is launched.
+        launchBrowserIfNecessary(context);
+
+        mTaskFinishedCallback = callback;
+        return nativeStartPrefetchTask(mProfile);
+    }
+
+    @Override
+    public boolean onStopTask(Context context, TaskParameters taskParameters) {
+        assert taskParameters.getTaskId() == TaskIds.OFFLINE_PAGES_PREFETCH_JOB_ID;
+        if (mNativeTask == 0) return false;
+
+        return nativeOnStopTask(mNativeTask);
+    }
+
+    /**
+     * Called during construction of the native task.
+     *
+     * PrefetchBackgroundTask#onStartTask constructs the native task.
+     */
+    @VisibleForTesting
+    @CalledByNative
+    void setNativeTask(long nativeTask) {
+        mNativeTask = nativeTask;
+    }
+
+    /**
+     * Invoked by the native task when it is destroyed.
+     */
+    @VisibleForTesting
+    @CalledByNative
+    void doneProcessing(boolean needsReschedule) {
+        assert mTaskFinishedCallback != null;
+        mTaskFinishedCallback.taskFinished(needsReschedule);
+        setNativeTask(0);
+    }
+
+    @VisibleForTesting
+    @SuppressFBWarnings("DM_EXIT")
+    void launchBrowserIfNecessary(Context context) {
+        if (BrowserStartupController.get(LibraryProcessType.PROCESS_BROWSER)
+                        .isStartupSuccessfullyCompleted()) {
+            return;
+        }
+
+        // TODO(https://crbug.com/717251): Remove when BackgroundTaskScheduler supports loading the
+        // native library.
+        try {
+            ChromeBrowserInitializer.getInstance(context).handleSynchronousStartup();
+        } catch (ProcessInitException e) {
+            Log.e(TAG, "ProcessInitException while starting the browser process.");
+            // Since the library failed to initialize nothing in the application can work, so kill
+            // the whole application not just the activity.
+            System.exit(-1);
+        }
+    }
+
+    @VisibleForTesting
+    native boolean nativeStartPrefetchTask(Profile profile);
+    @VisibleForTesting
+    native boolean nativeOnStopTask(long nativePrefetchBackgroundTask);
+}