Calling start/stop listening in onStart/onStop

AppWidgetHost in N-MR1 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: I1f40a1ddc51a9eee304e17e72106bc75afe6c1bc
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index 97af37c..7a4e4f0 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -950,6 +950,10 @@
         if (mLauncherCallbacks != null) {
             mLauncherCallbacks.onStop();
         }
+
+        if (Utilities.isNycMR1OrAbove()) {
+            mAppWidgetHost.stopListening();
+        }
     }
 
     @Override
@@ -960,6 +964,10 @@
         if (mLauncherCallbacks != null) {
             mLauncherCallbacks.onStart();
         }
+
+        if (Utilities.isNycMR1OrAbove()) {
+            mAppWidgetHost.startListening();
+        }
     }
 
     @Override