Fragmentize UserDictionary.

Depending on I2c962726b0adc8811c18dd6df7ff7bdc93c31a07, which
implements DialogCreatable.

Change-Id: I9857e592218731bfbddc578c15180cc681fa4d20
diff --git a/src/com/android/settings/SettingsPreferenceFragment.java b/src/com/android/settings/SettingsPreferenceFragment.java
index 2d37641..90ceb03 100644
--- a/src/com/android/settings/SettingsPreferenceFragment.java
+++ b/src/com/android/settings/SettingsPreferenceFragment.java
@@ -32,6 +32,11 @@
 import android.view.View.OnClickListener;
 import android.widget.Button;
 
+/**
+ * Letting the class, assumed to be Fragment, create a Dialog on it. Should be useful
+ * you want to utilize some capability in {@link SettingsPreferenceFragment} but don't want
+ * the class inherit the class itself (See {@link ProxySelector} for example).
+ */
 interface DialogCreatable {
     public Dialog onCreateDialog(int dialogId);
 }