Ensure we don't crash the system server when disabling/enabling package.

We shouldn't crash when trying to disable/enable a non-existent fallback
package.

Bug: 27918467
Change-Id: Ia94425ac197b17430900bb7a9e7b2d2bf65ab9b3

services/core/java/com/android/server/webkit/SystemImpl.java

@@ -19,6 +19,7 @@ package com.android.server.webkit;
 import android.app.ActivityManagerNative;
 import android.app.AppGlobals;
 import android.content.Context;
+import android.content.pm.ApplicationInfo;
 import android.content.pm.IPackageDeleteObserver;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
@@ -187,7 +188,8 @@ public class SystemImpl implements SystemInterface {
         enablePackageForAllUsers(context, packageName, false);
         try {
             PackageManager pm = AppGlobals.getInitialApplication().getPackageManager();
-            if (pm.getApplicationInfo(packageName, 0).isUpdatedSystemApp()) {
+            ApplicationInfo applicationInfo = pm.getApplicationInfo(packageName, 0);
+            if (applicationInfo != null && applicationInfo.isUpdatedSystemApp()) {
                 pm.deletePackage(packageName, new IPackageDeleteObserver.Stub() {
                         public void packageDeleted(String packageName, int returnCode) {
                             enablePackageForAllUsers(context, packageName, false);
@@ -214,8 +216,9 @@ public class SystemImpl implements SystemInterface {
                     enable ? PackageManager.COMPONENT_ENABLED_STATE_DEFAULT :
                     PackageManager.COMPONENT_ENABLED_STATE_DISABLED_USER, 0,
                     userId, null);
-        } catch (RemoteException e) {
-            Log.w(TAG, "Tried to disable " + packageName + " for user " + userId + ": " + e);
+        } catch (RemoteException | IllegalArgumentException e) {
+            Log.w(TAG, "Tried to " + (enable ? "enable " : "disable ") + packageName
+                    + " for user " + userId + ": " + e);
         }
     }
 

services/core/java/com/android/server/webkit/WebViewUpdateServiceImpl.java

@@ -160,6 +160,8 @@ public class WebViewUpdateServiceImpl {
             isFallbackEnabled = isEnabledPackage(
                     mSystemInterface.getPackageInfoForProvider(fallbackProvider));
         } catch (NameNotFoundException e) {
+            // No fallback package installed -> early out.
+            return;
         }
 
         if (existsValidNonFallbackProvider