Convert Magnify controller to TogglePrefController

Convert below to TogglePreferenceController:
MagnificationNavbarPreferenceController
(Magnify with Button)
MagnificationGesturesPreferenceController
(Magnify with triple-tap)

The two controllers share the same fragment,
Add static method for set/get state in fragment,
And use them in controllers and fragment.

Change-Id: I2bdbdb36be71e1a3ffb557abc5a6115d48de53cf
Fixes: 67997698
Fixes: 67997726
Test: make RunSettingsRoboTests

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

@@ -18,6 +18,7 @@ package com.android.settings.accessibility;
 
 import android.accessibilityservice.AccessibilityServiceInfo;
 import android.content.ComponentName;
+import android.content.ContentResolver;
 import android.content.Context;
 import android.content.res.Resources;
 import android.os.Bundle;
@@ -38,10 +39,15 @@ import com.android.settingslib.search.SearchIndexable;
 import java.util.Arrays;
 import java.util.List;
 
+import androidx.annotation.VisibleForTesting;
 import androidx.preference.Preference;
 
 @SearchIndexable
 public final class MagnificationPreferenceFragment extends DashboardFragment {
+    @VisibleForTesting
+    static final int ON = 1;
+    @VisibleForTesting
+    static final int OFF = 0;
 
     private static final String TAG = "MagnificationPreferenceFragment";
 
@@ -135,6 +141,15 @@ public final class MagnificationPreferenceFragment extends DashboardFragment {
         return null;
     }
 
+    static boolean isChecked(ContentResolver contentResolver, String settingsKey) {
+        return Settings.Secure.getInt(contentResolver, settingsKey, OFF) == ON;
+    }
+
+    static boolean setChecked(ContentResolver contentResolver, String settingsKey,
+            boolean isChecked) {
+        return Settings.Secure.putInt(contentResolver, settingsKey, isChecked ? ON : OFF);
+    }
+
     /**
      * @return {@code true} if this fragment should be shown, {@code false} otherwise. This
      * fragment is shown in the case that more than one magnification mode is available.