Add recent apps in app & notification

- Introduce a RecentAppsPreferenceControler, which queries
  UsageStatsManager and displays a list of recently used apps.

- Add a control flag for this feature, intially set to false.

- Make ManageApplications a static pref item instead of dynamic one.
  This makes the RecentAppController easier to control "See all"
  preference, which is backed by ManageApplications.

- Also adjust app_items.xml layout to make app item UI consistent with
  preference item.

Change-Id: I0b9e1784faed32b3055ebf96ef98b6a5e422de50
Fix: 33265548
Test: robotests

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

@@ -14,7 +14,6 @@
 
 package com.android.settings.applications;
 
-import android.app.AppGlobals;
 import android.content.Context;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
@@ -32,7 +31,7 @@ public abstract class AppCounter extends AsyncTask<Void, Void, Integer> {
 
     public AppCounter(Context context, PackageManagerWrapper packageManager) {
         mPm = packageManager;
-        mUm = UserManager.get(context);
+        mUm = (UserManager) context.getSystemService(Context.USER_SERVICE);
     }
 
     @Override