WebLayer: Remove media stream notifications from prior app instances.

When the app crashes, it can leave behind media streaming notifications.
Track these in a pref and remove on next startup.

We could use getActiveNotifications instead of storing a pref, but it's
only available in API 23.

Testing is still a todo and may be somewhat difficult as full
integration testing requires crashing the app. For now this is manually
tested by removing the cancel() calls that execute on stream/tab
destruction and restarting the app.

Bug: 1025622
Change-Id: Icdd475707ac1af0789968264c202e00fd8964d33
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2142394
Commit-Queue: Evan Stade <estade@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757944}

weblayer/browser/java/org/chromium/weblayer_private/MediaStreamManager.java

@@ -8,6 +8,7 @@ import android.app.NotificationChannel;
 import android.app.NotificationManager;
 import android.app.PendingIntent;
 import android.content.Intent;
+import android.content.SharedPreferences;
 import android.os.Build;
 import android.os.RemoteException;
 import android.util.AndroidRuntimeException;
@@ -21,11 +22,12 @@ import org.chromium.base.annotations.JNINamespace;
 import org.chromium.base.annotations.NativeMethods;
 import org.chromium.content_public.browser.WebContents;
 
+import java.util.HashSet;
+import java.util.Set;
+
 /**
  * A per-tab object that manages notifications for ongoing media streams (microphone/camera). This
  * object is created by {@link TabImpl} and creates and destroys its native equivalent.
- *
- * TODO(estade): remove notifications that have persisted across restarts (due to the app crashing).
  */
 @JNINamespace("weblayer")
 public class MediaStreamManager {
@@ -36,6 +38,15 @@ public class MediaStreamManager {
     private static final String ACTIVATE_TAB_INTENT = WEBRTC_PREFIX + ".ACTIVATE_TAB";
     private static final String AV_STREAM_TAG = WEBRTC_PREFIX + ".avstream";
 
+    /**
+     * A key used in the app's shared preferences to track a set of active streaming notifications.
+     * This is used to clear notifications that may have persisted across restarts due to a crash.
+     * TODO(estade): remove this approach and simply iterate across all notifications via
+     * {@link NotificationManager#getActiveNotifications} once the minimum API level is 23.
+     */
+    private static final String PREF_ACTIVE_AV_STREAM_NOTIFICATION_IDS =
+            WEBRTC_PREFIX + ".avstream_notifications";
+
     // The notification ID matches the tab ID, which uniquely identifies the notification when
     // paired with the tag.
     private int mNotificationId;
@@ -67,17 +78,62 @@ public class MediaStreamManager {
         }
     }
 
+    /**
+     * To be called when WebLayer is started. Clears notifications that may have persisted from
+     * before a crash.
+     */
+    public static void onWebLayerInit() {
+        SharedPreferences prefs = ContextUtils.getAppSharedPreferences();
+        Set<String> staleNotificationIds =
+                prefs.getStringSet(PREF_ACTIVE_AV_STREAM_NOTIFICATION_IDS, null);
+        if (staleNotificationIds == null) return;
+
+        NotificationManagerCompat manager = getNotificationManager();
+        if (manager == null) return;
+
+        for (String id : staleNotificationIds) {
+            manager.cancel(AV_STREAM_TAG, Integer.parseInt(id));
+        }
+        prefs.edit().remove(PREF_ACTIVE_AV_STREAM_NOTIFICATION_IDS).apply();
+    }
+
     public MediaStreamManager(TabImpl tab) {
         mNotificationId = tab.getId();
         mNative = MediaStreamManagerJni.get().create(this, tab.getWebContents());
     }
 
     public void destroy() {
+        cancelNotification();
+        MediaStreamManagerJni.get().destroy(mNative);
+    }
+
+    private void cancelNotification() {
         NotificationManagerCompat notificationManager = getNotificationManager();
-        if (notificationManager == null) return;
+        if (notificationManager != null) {
             notificationManager.cancel(AV_STREAM_TAG, mNotificationId);
+        }
+        updateActiveNotifications(false);
+    }
 
-        MediaStreamManagerJni.get().destroy(mNative);
+    /**
+     * Updates the list of active notifications stored in the SharedPrefences.
+     *
+     * @param active if true, then {@link mNotificationId} will be added to the list of active
+     *         notifications, otherwise it will be removed.
+     */
+    private void updateActiveNotifications(boolean active) {
+        SharedPreferences prefs = ContextUtils.getAppSharedPreferences();
+        Set<String> activeIds = new HashSet<String>(
+                prefs.getStringSet(PREF_ACTIVE_AV_STREAM_NOTIFICATION_IDS, new HashSet<String>()));
+        if (active) {
+            activeIds.add(Integer.toString(mNotificationId));
+        } else {
+            activeIds.remove(Integer.toString(mNotificationId));
+        }
+        prefs.edit()
+                .putStringSet(PREF_ACTIVE_AV_STREAM_NOTIFICATION_IDS,
+                        activeIds.isEmpty() ? null : activeIds)
+                .apply();
     }
 
     /**
@@ -94,15 +150,15 @@ public class MediaStreamManager {
         // The notification intent is not handled in the client prior to M84.
         if (WebLayerFactoryImpl.getClientMajorVersion() < 84) return;
 
-        NotificationManagerCompat notificationManager = getNotificationManager();
-        if (notificationManager == null) return;
-        createNotificationChannel();
-
         if (!audio && !video) {
-            notificationManager.cancel(AV_STREAM_TAG, mNotificationId);
+            cancelNotification();
             return;
         }
 
+        NotificationManagerCompat notificationManager = getNotificationManager();
+        if (notificationManager == null) return;
+        createNotificationChannel();
+
         Intent intent = WebLayerImpl.createIntent();
         intent.putExtra(EXTRA_TAB_ID, mNotificationId);
         intent.setAction(ACTIVATE_TAB_INTENT);
@@ -120,6 +176,7 @@ public class MediaStreamManager {
                                         ? "all the streamz"
                                         : audio ? "audio streamz" : "video streamz");
         notificationManager.notify(AV_STREAM_TAG, mNotificationId, builder.build());
+        updateActiveNotifications(true);
     }
 
     private void createNotificationChannel() {
@@ -136,7 +193,7 @@ public class MediaStreamManager {
         sCreatedChannel = true;
     }
 
-    private NotificationManagerCompat getNotificationManager() {
+    private static NotificationManagerCompat getNotificationManager() {
         if (ContextUtils.getApplicationContext() == null) {
             return null;
         }

weblayer/browser/java/org/chromium/weblayer_private/WebLayerImpl.java

@@ -259,6 +259,8 @@ public final class WebLayerImpl extends IWebLayer.Stub {
             LibraryLoader.getInstance().ensureInitialized();
         }
         GmsBridge.getInstance().setSafeBrowsingHandler();
+
+        MediaStreamManager.onWebLayerInit();
     }
 
     @Override