Skip redundant SuggestionLoader run during app start.

also skip DiffUtil when drawing first frame.


Fix: 34103984
Test: make RunSettingsRoboTests
Change-Id: I4891d1bca1f17c437444761eaf3002624934014d

tests/robotests/src/com/android/settings/dashboard/DashboardSummaryTest.java

@@ -17,8 +17,8 @@
 package com.android.settings.dashboard;
 
 import android.app.Activity;
-
 import android.support.v7.widget.LinearLayoutManager;
+
 import com.android.settings.SettingsRobolectricTestRunner;
 import com.android.settings.TestConfig;
 import com.android.settings.dashboard.conditional.ConditionManager;
@@ -33,6 +33,7 @@ import org.mockito.MockitoAnnotations;
 import org.robolectric.annotation.Config;
 import org.robolectric.util.ReflectionHelpers;
 
+import static org.mockito.Matchers.anyList;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
@@ -90,4 +91,13 @@ public class DashboardSummaryTest {
         mSummary.onConditionsChanged();
         verify(mDashboard, never()).scrollToPosition(0);
     }
+
+    @Test
+    public void onCategoryChanged_updateCategoryOnly() {
+        doReturn(mock(Activity.class)).when(mSummary).getActivity();
+        when(mDashboardFeatureProvider.isEnabled()).thenReturn(true);
+
+        mSummary.onCategoriesChanged();
+        verify(mAdapter).setCategory(anyList());
+    }
 }