Log a-z apps count.

Test: manual
Bug: 247432075
Change-Id: I9538a75bc3cb3d1e8e9089fc5e27d5d770cafb62

src/com/android/launcher3/allapps/BaseAllAppsContainerView.java

@@ -15,6 +15,7 @@
  */
 package com.android.launcher3.allapps;
 
+import static com.android.launcher3.logging.StatsLogManager.LauncherEvent.LAUNCHER_ALLAPPS_COUNT;
 import static com.android.launcher3.logging.StatsLogManager.LauncherEvent.LAUNCHER_ALLAPPS_TAP_ON_PERSONAL_TAB;
 import static com.android.launcher3.logging.StatsLogManager.LauncherEvent.LAUNCHER_ALLAPPS_TAP_ON_WORK_TAB;
 
@@ -244,6 +245,10 @@ public abstract class BaseAllAppsContainerView<T extends Context & ActivityConte
                 mWorkManager.reset();
             }
         }
+
+        mActivityContext.getStatsLogManager().logger()
+                .withCardinality(mAllAppsStore.getApps().length)
+                .log(LAUNCHER_ALLAPPS_COUNT);
     }
 
     /**