SettingsLib: Fix possible NPEs

getText() can return null, resulting in a NPE when trying to call
toString(). Add a null check to prevent this.
Additionally add a null check for packageInfo, as this can also be null.

Change-Id: Ia76326522872f4de4702ef56640b2f7b357c2bb7
Reference: BugDumps 20161104-10 L#135

Author: BadDaemon

packages/SettingsLib/src/com/android/settingslib/net/UidDetailProvider.java

@@ -166,13 +166,16 @@ private UidDetail buildUidDetail(int uid) {
                     final ApplicationInfo appInfo = ipm.getApplicationInfo(packageName,
                             0 /* no flags */, userId);
 
-                    if (appInfo != null) {
+                    if (appInfo != null && packageInfo != null) {
                         detail.detailLabels[i] = appInfo.loadLabel(pm).toString();
                         detail.detailContentDescriptions[i] = um.getBadgedLabelForUser(
                                 detail.detailLabels[i], userHandle);
                         if (packageInfo.sharedUserLabel != 0) {
-                            detail.label = pm.getText(packageName, packageInfo.sharedUserLabel,
-                                    packageInfo.applicationInfo).toString();
+                            CharSequence label = pm.getText(packageName,
+                                    packageInfo.sharedUserLabel, packageInfo.applicationInfo);
+                            if (label != null) {
+                                detail.label = label.toString();
+                            }
                             detail.icon = um.getBadgedIconForUser(appInfo.loadIcon(pm), userHandle);
                         }
                     }