Fix crash after adding a word to the user dictionary.

Bug: 3407951

Make sure that the parent fragment is a SettingsPreferenceFragment. Otherwise it's not
necessary to manage the mDialogFragment.

Change-Id: I331a3507fe11a7331ff24ecf64fe8c8c3f613636

src/com/android/settings/SettingsPreferenceFragment.java

@@ -182,9 +182,12 @@ public class SettingsPreferenceFragment extends PreferenceFragment
                                         + DialogCreatable.class.getName());
                     }
                 }
+                // This dialog fragment could be created from non-SettingsPreferenceFragment
+                if (mParentFragment instanceof SettingsPreferenceFragment) {
                     // restore mDialogFragment in mParentFragment
                     ((SettingsPreferenceFragment) mParentFragment).mDialogFragment = this;
                 }
+            }
             return ((DialogCreatable) mParentFragment).onCreateDialog(mDialogId);
         }
 
@@ -203,6 +206,7 @@ public class SettingsPreferenceFragment extends PreferenceFragment
                 mOnDismissListener.onDismiss(dialog);
             }
         }
+
         public int getDialogId() {
             return mDialogId;
         }
@@ -211,12 +215,15 @@ public class SettingsPreferenceFragment extends PreferenceFragment
         public void onDetach() {
             super.onDetach();
 
+            // This dialog fragment could be created from non-SettingsPreferenceFragment
+            if (mParentFragment instanceof SettingsPreferenceFragment) {
                 // in case the dialog is not explicitly removed by removeDialog()
                 if (((SettingsPreferenceFragment) mParentFragment).mDialogFragment == this) {
                     ((SettingsPreferenceFragment) mParentFragment).mDialogFragment = null;
                 }
             }
         }
+    }
 
     protected boolean hasNextButton() {
         return ((ButtonBarHandler)getActivity()).hasNextButton();