Guard against null Context in attachInfo().

Some CTS tests were running into this.

Bug: 10805216
Change-Id: I425d2a0064612af70a64f457e159498cb6257a28
diff --git a/core/java/android/content/ContentProvider.java b/core/java/android/content/ContentProvider.java
index 0a1d3f9a..9a258dc 100644
--- a/core/java/android/content/ContentProvider.java
+++ b/core/java/android/content/ContentProvider.java
@@ -1573,8 +1573,10 @@
          */
         if (mContext == null) {
             mContext = context;
-            mTransport.mAppOpsManager = (AppOpsManager) mContext.getSystemService(
-                    Context.APP_OPS_SERVICE);
+            if (context != null) {
+                mTransport.mAppOpsManager = (AppOpsManager) context.getSystemService(
+                        Context.APP_OPS_SERVICE);
+            }
             mMyUid = Process.myUid();
             if (info != null) {
                 setReadPermission(info.readPermission);