Speed up dev options

- Put memory updates on background thread
 - Prevent update state from being called twice

Bug: 69000975
Test: Manual
Change-Id: I186bc25f6b74a5098b1737891efee3a6855dc996

tests/robotests/src/com/android/settings/development/MemoryUsagePreferenceControllerTest.java

@@ -30,6 +30,7 @@ import android.support.v7.preference.PreferenceScreen;
 import com.android.settings.TestConfig;
 import com.android.settings.applications.ProcStatsData;
 import com.android.settings.testutils.SettingsRobolectricTestRunner;
+import com.android.settings.testutils.shadow.ShadowThreadUtils;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -68,6 +69,9 @@ public class MemoryUsagePreferenceControllerTest {
     }
 
     @Test
+    @Config(shadows = {
+            ShadowThreadUtils.class
+    })
     public void updateState_shouldUpdatePreferenceSummary() {
         mController.updateState(mPreference);