Revert "Download notification: Simplify foreground notification events."

This reverts commit bfb35d53.

Reason for revert: Triggers a bug in the old code. see crbug/1056107.

Original change's description:
> Download notification: Simplify foreground notification events.
> 
> Currently we use DownloadForegroundServiceObservers to broadcast
> download foreground service events. It uses reflection to cache the
> class name and then persist to android shared preference.
> 
> DownloadNotificationServiceObserver implements
> DownloadForegroundServiceObservers.Observer, and then call methods of
> the singleton object of DownloadNotificationService.
> 
> Also, onForegroundServiceRestarted() is not getting called, which make
> the following calls dead code.
> 
> This is extremely weird, we can just call the one line singleton
> method.
> 
> Bug: 922929
> Change-Id: I28ff5552fd7fc0fd5a111cd4971d6bf4514bb45f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2063853
> Reviewed-by: David Trainor <dtrainor@chromium.org>
> Commit-Queue: Xing Liu <xingliu@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#743368}

TBR=dtrainor@chromium.org,qinmin@chromium.org,xingliu@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 922929
Change-Id: I467b19ba958a380a08e464339e735d5e30e376c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2076977Reviewed-by: Xing Liu <xingliu@chromium.org>
Commit-Queue: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745156}

chrome/android/chrome_java_sources.gni

@@ -506,6 +506,7 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/download/DownloadController.java",
   "java/src/org/chromium/chrome/browser/download/DownloadForegroundService.java",
   "java/src/org/chromium/chrome/browser/download/DownloadForegroundServiceManager.java",
+  "java/src/org/chromium/chrome/browser/download/DownloadForegroundServiceObservers.java",
   "java/src/org/chromium/chrome/browser/download/DownloadInfoBarController.java",
   "java/src/org/chromium/chrome/browser/download/DownloadItem.java",
   "java/src/org/chromium/chrome/browser/download/DownloadLocationCustomView.java",
@@ -514,6 +515,7 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/download/DownloadMetrics.java",
   "java/src/org/chromium/chrome/browser/download/DownloadNotificationFactory.java",
   "java/src/org/chromium/chrome/browser/download/DownloadNotificationService.java",
+  "java/src/org/chromium/chrome/browser/download/DownloadNotificationServiceObserver.java",
   "java/src/org/chromium/chrome/browser/download/DownloadNotificationUmaHelper.java",
   "java/src/org/chromium/chrome/browser/download/DownloadNotifier.java",
   "java/src/org/chromium/chrome/browser/download/DownloadPage.java",

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadForegroundService.java

@@ -187,7 +187,7 @@ public class DownloadForegroundService extends Service {
     public void onDestroy() {
         DownloadNotificationUmaHelper.recordServiceStoppedHistogram(
                 DownloadNotificationUmaHelper.ServiceStopped.DESTROYED, true /* withForeground */);
-        DownloadNotificationService.getInstance().onForegroundServiceDestroyed();
+        DownloadForegroundServiceObservers.alertObserversServiceDestroyed();
         super.onDestroy();
     }
 
@@ -195,7 +195,7 @@ public class DownloadForegroundService extends Service {
     public void onTaskRemoved(Intent rootIntent) {
         DownloadNotificationUmaHelper.recordServiceStoppedHistogram(
                 DownloadNotificationUmaHelper.ServiceStopped.TASK_REMOVED, true /*withForeground*/);
-        DownloadNotificationService.getInstance().onForegroundServiceTaskRemoved();
+        DownloadForegroundServiceObservers.alertObserversTaskRemoved();
         super.onTaskRemoved(rootIntent);
     }
 

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadForegroundServiceManager.java

@@ -212,6 +212,8 @@ public class DownloadForegroundServiceManager {
                 return;
             }
             mBoundService = ((DownloadForegroundService.LocalBinder) service).getService();
+            DownloadForegroundServiceObservers.addObserver(
+                    DownloadNotificationServiceObserver.class);
             processDownloadUpdateQueue(true /* isProcessingPending */);
         }
 
@@ -282,6 +284,9 @@ public class DownloadForegroundServiceManager {
         mBoundService.stopDownloadForegroundService(
                 stopForegroundStatus, pinnedNotificationId, pinnedNotification);
         ContextUtils.getApplicationContext().unbindService(mConnection);
+
+        DownloadForegroundServiceObservers.removeObserver(
+                DownloadNotificationServiceObserver.class);
     }
 
     /** Helper code for testing. */

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadForegroundServiceObservers.java

+// 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.download;
+
+import androidx.annotation.Nullable;
+
+import org.chromium.base.Log;
+import org.chromium.base.ThreadUtils;
+import org.chromium.chrome.browser.preferences.ChromePreferenceKeys;
+import org.chromium.chrome.browser.preferences.SharedPreferencesManager;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * A class that handles logic related to observers that are waiting to see when the
+ * DownloadsForegroundService is shutting down or starting back up.
+ */
+public final class DownloadForegroundServiceObservers {
+    private static final String TAG = "DownloadFgServiceObs";
+
+    /**
+     * An Observer interfaces that allows other classes to know when this service is shutting down.
+     * Implementing classes must be marked as @UsedByReflection in order to prevent the class name
+     * from being obfuscated.
+     * Implementing classes must also have a public parameterless constructor that is marked as
+     * @UsedByReflection.
+     * Implementing classes may never be renamed, as class names are persisted between app updates.
+     */
+    public interface Observer {
+        /**
+         * Called when the foreground service was automatically restarted because of START_STICKY.
+         * @param pinnedNotificationId Id of the notification pinned to the service when it died.
+         */
+        void onForegroundServiceRestarted(int pinnedNotificationId);
+
+        /**
+         * Called when any task (service or activity) is removed from the service's application.
+         */
+        void onForegroundServiceTaskRemoved();
+
+        /**
+         * Called when the foreground service is destroyed.
+         *
+         */
+        void onForegroundServiceDestroyed();
+    }
+
+    /**
+     * Adds an observer, which will be notified when this service attempts to start stopping itself.
+     * @param observerClass to be added to the list of observers in SharedPrefs.
+     */
+    public static void addObserver(Class<? extends Observer> observerClass) {
+        ThreadUtils.assertOnUiThread();
+
+        Set<String> observers = getAllObservers();
+        String observerClassName = observerClass.getName();
+        if (observers.contains(observerClassName)) return;
+
+        // Set returned from getStringSet() should not be modified.
+        observers = new HashSet<>(observers);
+        observers.add(observerClassName);
+
+        SharedPreferencesManager.getInstance().writeStringSet(
+                ChromePreferenceKeys.DOWNLOAD_FOREGROUND_SERVICE_OBSERVERS, observers);
+    }
+
+    /**
+     * Removes observer, which will no longer be notified when this class starts stopping itself.
+     * @param observerClass to be removed from the list of observers in SharedPrefs.
+     */
+    public static void removeObserver(Class<? extends Observer> observerClass) {
+        ThreadUtils.assertOnUiThread();
+
+        Set<String> observers = getAllObservers();
+        String observerClassName = observerClass.getName();
+        if (!observers.contains(observerClassName)) return;
+
+        // Set returned from getStringSet() should not be modified.
+        observers = new HashSet<>(observers);
+        observers.remove(observerClassName);
+
+        // Clear observer list if there are none.
+        if (observers.size() == 0) {
+            removeAllObservers();
+            return;
+        }
+
+        SharedPreferencesManager.getInstance().writeStringSet(
+                ChromePreferenceKeys.DOWNLOAD_FOREGROUND_SERVICE_OBSERVERS, observers);
+    }
+
+    static void alertObserversServiceRestarted(int pinnedNotificationId) {
+        Set<String> observers = getAllObservers();
+        removeAllObservers();
+
+        for (String observerClassName : observers) {
+            DownloadForegroundServiceObservers.Observer observer =
+                    DownloadForegroundServiceObservers.getObserverFromClassName(observerClassName);
+            if (observer != null) observer.onForegroundServiceRestarted(pinnedNotificationId);
+        }
+    }
+
+    static void alertObserversServiceDestroyed() {
+        Set<String> observers = getAllObservers();
+
+        for (String observerClassName : observers) {
+            DownloadForegroundServiceObservers.Observer observer =
+                    DownloadForegroundServiceObservers.getObserverFromClassName(observerClassName);
+            if (observer != null) observer.onForegroundServiceDestroyed();
+        }
+    }
+
+    static void alertObserversTaskRemoved() {
+        Set<String> observers = getAllObservers();
+
+        for (String observerClassName : observers) {
+            Observer observer = getObserverFromClassName(observerClassName);
+            if (observer != null) observer.onForegroundServiceTaskRemoved();
+        }
+    }
+
+    private static Set<String> getAllObservers() {
+        return SharedPreferencesManager.getInstance().readStringSet(
+                ChromePreferenceKeys.DOWNLOAD_FOREGROUND_SERVICE_OBSERVERS);
+    }
+
+    private static void removeAllObservers() {
+        SharedPreferencesManager.getInstance().removeKey(
+                ChromePreferenceKeys.DOWNLOAD_FOREGROUND_SERVICE_OBSERVERS);
+    }
+
+    @Nullable
+    private static Observer getObserverFromClassName(String observerClassName) {
+        try {
+            Class<?> observerClass = Class.forName(observerClassName);
+            return (Observer) observerClass.newInstance();
+        } catch (Throwable e) {
+            Log.w(TAG, "getObserverFromClassName(): %s", observerClassName, e);
+            return null;
+        }
+    }
+}

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadNotificationService.java

@@ -5,6 +5,7 @@
 package org.chromium.chrome.browser.download;
 
 import static org.chromium.chrome.browser.download.DownloadBroadcastManager.getServiceDelegate;
+import static org.chromium.chrome.browser.download.DownloadSnackbarController.INVALID_NOTIFICATION_ID;
 
 import android.app.Notification;
 import android.content.Context;
@@ -634,6 +635,16 @@ public class DownloadNotificationService {
                 ChromePreferenceKeys.DOWNLOAD_AUTO_RESUMPTION_ATTEMPT_LEFT);
     }
 
+    void onForegroundServiceRestarted(int pinnedNotificationId) {
+        // In API < 24, notifications pinned to the foreground will get killed with the service.
+        // Fix this by relaunching the notification that was pinned to the service as the service
+        // dies, if there is one.
+        relaunchPinnedNotification(pinnedNotificationId);
+
+        updateNotificationsForShutdown();
+        resumeAllPendingDownloads();
+    }
+
     void onForegroundServiceTaskRemoved() {
         // If we've lost all Activities, cancel the off the record downloads.
         if (ApplicationStatus.isEveryActivityDestroyed()) {
@@ -646,6 +657,39 @@ public class DownloadNotificationService {
         rescheduleDownloads();
     }
 
+    /**
+     * Given the id of the notification that was pinned to the service when it died, give the
+     * notification a new id in order to rebuild and relaunch the notification.
+     * @param pinnedNotificationId Id of the notification pinned to the service when it died.
+     */
+    private void relaunchPinnedNotification(int pinnedNotificationId) {
+        // If there was no notification pinned to the service, no correction is necessary.
+        if (pinnedNotificationId == INVALID_NOTIFICATION_ID) return;
+
+        List<DownloadSharedPreferenceEntry> entries = mDownloadSharedPreferenceHelper.getEntries();
+        List<DownloadSharedPreferenceEntry> copies =
+                new ArrayList<DownloadSharedPreferenceEntry>(entries);
+        for (DownloadSharedPreferenceEntry entry : copies) {
+            if (entry.notificationId == pinnedNotificationId) {
+                // Get new notification id that is not associated with the service.
+                DownloadSharedPreferenceEntry updatedEntry =
+                        new DownloadSharedPreferenceEntry(entry.id, getNextNotificationId(),
+                                entry.isOffTheRecord, entry.canDownloadWhileMetered, entry.fileName,
+                                entry.isAutoResumable, entry.isTransient);
+                mDownloadSharedPreferenceHelper.addOrReplaceSharedPreferenceEntry(updatedEntry);
+
+                // Right now this only happens in the paused case, so re-build and re-launch the
+                // paused notification, with the updated notification id..
+                notifyDownloadPaused(updatedEntry.id, updatedEntry.fileName, true /* isResumable */,
+                        updatedEntry.isAutoResumable, updatedEntry.isOffTheRecord,
+                        updatedEntry.isTransient, null /* icon */, null /* originalUrl */,
+                        false /* shouldPromoteOrigin */, true /* hasUserGesture */,
+                        true /* forceRebuild */, PendingState.NOT_PENDING);
+                return;
+            }
+        }
+    }
+
     private void updateNotificationsForShutdown() {
         cancelOffTheRecordDownloads();
         List<DownloadSharedPreferenceEntry> entries = mDownloadSharedPreferenceHelper.getEntries();

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadNotificationServiceObserver.java

+// 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.download;
+
+import org.chromium.base.annotations.UsedByReflection;
+
+/**
+ * A DownloadForegroundServiceObservers.Observer implementation for DownloadNotificationService.
+ */
+@UsedByReflection("DownloadForegroundServiceObservers")
+public class DownloadNotificationServiceObserver
+        implements DownloadForegroundServiceObservers.Observer {
+    @UsedByReflection("DownloadForegroundServiceObservers")
+    public DownloadNotificationServiceObserver() {}
+
+    @Override
+    public void onForegroundServiceRestarted(int pinnedNotificationId) {
+        DownloadNotificationService.getInstance().onForegroundServiceRestarted(
+                pinnedNotificationId);
+    }
+
+    @Override
+    public void onForegroundServiceTaskRemoved() {
+        DownloadNotificationService.getInstance().onForegroundServiceTaskRemoved();
+    }
+
+    @Override
+    public void onForegroundServiceDestroyed() {
+        DownloadNotificationService.getInstance().onForegroundServiceDestroyed();
+    }
+}

chrome/browser/preferences/android/java/src/org/chromium/chrome/browser/preferences/ChromePreferenceKeys.java

@@ -246,6 +246,7 @@ public final class ChromePreferenceKeys {
             "data_reduction_site_breakdown_allowed_date";
 
     public static final String DOWNLOAD_AUTO_RESUMPTION_ATTEMPT_LEFT = "ResumptionAttemptLeft";
+    public static final String DOWNLOAD_FOREGROUND_SERVICE_OBSERVERS = "ForegroundServiceObservers";
     public static final String DOWNLOAD_IS_DOWNLOAD_HOME_ENABLED =
             "org.chromium.chrome.browser.download.IS_DOWNLOAD_HOME_ENABLED";
     public static final String DOWNLOAD_NEXT_DOWNLOAD_NOTIFICATION_ID =
@@ -694,7 +695,6 @@ public final class ChromePreferenceKeys {
     static List<String> createDeprecatedKeysForTesting() {
         // clang-format off
         return Arrays.asList(
-                "ForegroundServiceObservers",
                 "PersistedNotificationId",
                 "PhysicalWeb.ActivityReferral",
                 "PhysicalWeb.HasDeferredMetrics",
@@ -805,6 +805,7 @@ public final class ChromePreferenceKeys {
                 DATA_REDUCTION_FRE_PROMO_OPT_OUT,
                 DATA_REDUCTION_SITE_BREAKDOWN_ALLOWED_DATE,
                 DOWNLOAD_AUTO_RESUMPTION_ATTEMPT_LEFT,
+                DOWNLOAD_FOREGROUND_SERVICE_OBSERVERS,
                 DOWNLOAD_IS_DOWNLOAD_HOME_ENABLED,
                 DOWNLOAD_NEXT_DOWNLOAD_NOTIFICATION_ID,
                 DOWNLOAD_PENDING_DOWNLOAD_NOTIFICATIONS,