Calling start/stop listening in onStart/onStop

AppWidgetHost in N was changed to make start/stop lisenting calls
light weight, which allows launcher to avoid getting unnecessary
updates when its not visible

Bug: 23892701
Change-Id: I0ca6e02400992bc4e0359e45a3d66b9252751402
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index 445831c..ba5ec51 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -963,6 +963,9 @@
     protected void onStop() {
         super.onStop();
         FirstFrameAnimatorHelper.setIsVisible(false);
+        if (Utilities.isNycOrAbove()) {
+            mAppWidgetHost.stopListening();
+        }
 
         if (mLauncherCallbacks != null) {
             mLauncherCallbacks.onStop();
@@ -973,6 +976,9 @@
     protected void onStart() {
         super.onStart();
         FirstFrameAnimatorHelper.setIsVisible(true);
+        if (Utilities.isNycOrAbove()) {
+            mAppWidgetHost.startListening();
+        }
 
         if (mLauncherCallbacks != null) {
             mLauncherCallbacks.onStart();