Don't crash if the backup transport supplies bogus intents

Preflight the (activity) intents supplied by the transport so that when
clicked, they don't crash the Preference that called startActivity().

Bug 27689847

Change-Id: I7cbdd6077ac74500ecdf9607310727af56d55a3c

src/com/android/settings/PrivacySettings.java

@@ -21,6 +21,8 @@ import android.app.backup.IBackupManager;
 import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.content.pm.ResolveInfo;
 import android.os.Bundle;
 import android.os.RemoteException;
 import android.os.ServiceManager;
@@ -155,9 +157,11 @@ public class PrivacySettings extends SettingsPreferenceFragment implements Index
         try {
             backupEnabled = mBackupManager.isBackupEnabled();
             String transport = mBackupManager.getCurrentTransport();
-            configIntent = mBackupManager.getConfigurationIntent(transport);
+            configIntent = validatedActivityIntent(
+                    mBackupManager.getConfigurationIntent(transport), "config");
             configSummary = mBackupManager.getDestinationString(transport);
-            manageIntent = mBackupManager.getDataManagementIntent(transport);
+            manageIntent = validatedActivityIntent(
+                    mBackupManager.getDataManagementIntent(transport), "management");
             manageLabel = mBackupManager.getDataManagementLabel(transport);
 
             mBackup.setSummary(backupEnabled
@@ -189,6 +193,19 @@ public class PrivacySettings extends SettingsPreferenceFragment implements Index
         }
     }
 
+    private Intent validatedActivityIntent(Intent intent, String logLabel) {
+        if (intent != null) {
+            PackageManager pm = getPackageManager();
+            List<ResolveInfo> resolved = pm.queryIntentActivities(intent, 0);
+            if (resolved == null || resolved.isEmpty()) {
+                intent = null;
+                Log.e(TAG, "Backup " + logLabel + " intent " + intent
+                        + " fails to resolve; ignoring");
+            }
+        }
+        return intent;
+    }
+
     private void setConfigureSummary(String summary) {
         if (summary != null) {
             mConfigure.setSummary(summary);