Improve launch time for app & notification screen

- We won't query recent apps in getAvailabilityStatus().
And then we do that in background thread.
So, we can launch app & notificatins screen as soon as possible.

- Create a RecentAppStatsMixin class which is responsible
for maintaining the recent apps data.

- Controllers and fragment update their UI after they got
onReloadDataCompleted callback from RecentAppStatsMixin.

Test: manual, robotest
Fixes: 128849426
Fixes: 126453868
Change-Id: I636d5878cb5d53496978fe613c625382d8d382bc

src/com/android/settings/applications/AllAppsInfoPreferenceController.java

@@ -19,39 +19,54 @@ package com.android.settings.applications;
 import android.app.usage.UsageStats;
 import android.content.Context;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.VisibleForTesting;
 import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
 
 import com.android.settings.R;
 import com.android.settings.core.BasePreferenceController;
 
 import java.util.List;
 
-public class AllAppsInfoPreferenceController extends BasePreferenceController {
+public class AllAppsInfoPreferenceController extends BasePreferenceController
+        implements RecentAppStatsMixin.RecentAppStatsListener {
 
-    private List<UsageStats> mRecentApps;
+    @VisibleForTesting
+    Preference mPreference;
 
     public AllAppsInfoPreferenceController(Context context, String key) {
         super(context, key);
     }
 
-    public void setRecentApps(List<UsageStats> recentApps) {
-        mRecentApps = recentApps;
-    }
-
     @Override
     public int getAvailabilityStatus() {
-        return mRecentApps == null || mRecentApps.isEmpty() ? AVAILABLE : CONDITIONALLY_UNAVAILABLE;
+        return AVAILABLE;
     }
 
     @Override
-    public void updateState(Preference preference) {
-        super.updateState(preference);
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mPreference = screen.findPreference(getPreferenceKey());
+        // In most cases, device has recently opened apps. So, we hide it by default.
+        mPreference.setVisible(false);
+    }
+
+    @Override
+    public void onReloadDataCompleted(@NonNull List<UsageStats> recentApps) {
+        // If device has recently opened apps, we don't show all apps preference.
+        if (!recentApps.isEmpty()) {
+            mPreference.setVisible(false);
+            return;
+        }
+
+        mPreference.setVisible(true);
         // Show total number of installed apps as See all's summary.
         new InstalledAppCounter(mContext, InstalledAppCounter.IGNORE_INSTALL_REASON,
                 mContext.getPackageManager()) {
             @Override
             protected void onCountComplete(int num) {
-                preference.setSummary(mContext.getString(R.string.apps_summary, num));
+                mPreference.setSummary(mContext.getString(R.string.apps_summary, num));
             }
         }.execute();
     }