Fix talkback issue of header preference

Header preference was just a static preference and used LayoutPreference
to show customized layout. But Preference default enabled the selectable
attribute, then caused the a11y service to speak out "Double-tap to
activate". Override the selectable attribute to fix it.

Fixes: 132856214
Test: robotests, visual
Change-Id: Ibc577de347edb66ab9de53f6177ca068a19ffa74

src/com/android/settings/SettingsPreferenceFragment.java

@@ -275,11 +275,13 @@ public abstract class SettingsPreferenceFragment extends InstrumentedPreferenceF
 
     protected void setHeaderView(int resource) {
         mHeader = new LayoutPreference(getPrefContext(), resource);
+        mHeader.setSelectable(false);
         addPreferenceToTop(mHeader);
     }
 
     protected void setHeaderView(View view) {
         mHeader = new LayoutPreference(getPrefContext(), view);
+        mHeader.setSelectable(false);
         addPreferenceToTop(mHeader);
     }