Hide Bluetooth, Reset, Accessibility Settings in ARC

This is an upstreaming change of http://ag/8541963 and
http://ag/10296201 to hide some items from settings search.

This CL also adds javadoc to some settings classes to fix pre-upload
warnings.

Bug: 153704887
Test: Manual. In ARC build, "bluetooth" and "accessibility" no longer shows related settings.
Change-Id: Ic3e9217944251adbea1bdd67baf66d3a9e89583a

src/com/android/settings/accessibility/MagnificationPreferenceFragment.java

@@ -39,12 +39,11 @@ import com.android.settingslib.search.SearchIndexable;
 
 import java.util.List;
 
-@SearchIndexable
+/** Settings fragment containing magnification preference. */
+@SearchIndexable(forTarget = SearchIndexable.ALL & ~SearchIndexable.ARC)
 public final class MagnificationPreferenceFragment extends DashboardFragment {
-    @VisibleForTesting
-    static final int ON = 1;
-    @VisibleForTesting
-    static final int OFF = 0;
+    @VisibleForTesting static final int ON = 1;
+    @VisibleForTesting static final int OFF = 0;
 
     private static final String TAG = "MagnificationPreferenceFragment";
 
@@ -169,4 +168,4 @@ public final class MagnificationPreferenceFragment extends DashboardFragment {
                     return isApplicable(context.getResources());
                 }
             };
-}
+}