Fix race condition and optimize categoryUpdater refresh

- In SettingsActivity, do not call updateCategories() if nothing
  changed.
- In SummaryLoader, create a mapping between tile key and summary. This
  is necessary to handle a race condition where category is refreshed
  after summary load.
- In DashboardSummary, refresh Tile's summary to latest cache value
  everytime category is refreshed.

Change-Id: I61389b8ba614ba7e34939325bada6e1bd6fa6709
Fix: 63149109
Test: robotests

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

@@ -19,11 +19,12 @@ package com.android.settings.dashboard;
 import android.app.Activity;
 import android.support.v7.widget.LinearLayoutManager;
 
-import com.android.settings.testutils.SettingsRobolectricTestRunner;
 import com.android.settings.TestConfig;
 import com.android.settings.dashboard.conditional.ConditionManager;
 import com.android.settings.dashboard.conditional.FocusRecyclerView;
+import com.android.settings.testutils.SettingsRobolectricTestRunner;
 import com.android.settingslib.drawer.CategoryKey;
+import com.android.settingslib.drawer.DashboardCategory;
 import com.android.settingslib.drawer.Tile;
 
 import org.junit.Before;
@@ -34,6 +35,7 @@ import org.mockito.MockitoAnnotations;
 import org.robolectric.annotation.Config;
 import org.robolectric.util.ReflectionHelpers;
 
+import static org.mockito.ArgumentMatchers.nullable;
 import static org.mockito.Mockito.doNothing;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
@@ -57,6 +59,8 @@ public class DashboardSummaryTest {
     private LinearLayoutManager mLayoutManager;
     @Mock
     private ConditionManager mConditionManager;
+    @Mock
+    private SummaryLoader mSummaryLoader;
 
     private DashboardSummary mSummary;
 
@@ -70,12 +74,15 @@ public class DashboardSummaryTest {
         ReflectionHelpers.setField(mSummary, "mDashboard", mDashboard);
         ReflectionHelpers.setField(mSummary, "mLayoutManager", mLayoutManager);
         ReflectionHelpers.setField(mSummary, "mConditionManager", mConditionManager);
+        ReflectionHelpers.setField(mSummary, "mSummaryLoader", mSummaryLoader);
     }
 
     @Test
     public void updateCategoryAndSuggestion_shouldGetCategoryFromFeatureProvider() {
         doReturn(mock(Activity.class)).when(mSummary).getActivity();
         mSummary.updateCategoryAndSuggestion(null);
+
+        verify(mSummaryLoader).updateSummaryToCache(nullable(DashboardCategory.class));
         verify(mDashboardFeatureProvider).getTilesForCategory(CategoryKey.CATEGORY_HOMEPAGE);
     }