Implement LauncherLayoutSnapshot pulled atom callback.

This change will pull only the workspace items but not the launcher settings such as grid layout etc. Future CLs will address it.

Bug: 181703659
Test: Manual-`statsd_testdrive 10108` http://gpaste/4894958784872448
Change-Id: I0e7d7da62034c411edb26ff9205a81b0e2e891a0
diff --git a/src/com/android/launcher3/LauncherAppState.java b/src/com/android/launcher3/LauncherAppState.java
index 86217d7..10023b4 100644
--- a/src/com/android/launcher3/LauncherAppState.java
+++ b/src/com/android/launcher3/LauncherAppState.java
@@ -138,10 +138,11 @@
         mContext = context;
 
         mInvariantDeviceProfile = InvariantDeviceProfile.INSTANCE.get(context);
-        mIconProvider =  new IconProvider(context, Themes.isThemedIconEnabled(context));
+        mIconProvider = new IconProvider(context, Themes.isThemedIconEnabled(context));
         mIconCache = new IconCache(mContext, mInvariantDeviceProfile,
                 iconCacheFileName, mIconProvider);
-        mModel = new LauncherModel(context, this, mIconCache, new AppFilter(mContext));
+        mModel = new LauncherModel(context, this, mIconCache, new AppFilter(mContext),
+                iconCacheFileName != null);
         mOnTerminateCallback.add(mIconCache::close);
     }