Move binder latency data logging to a background thread to improve performance of the main thread.

Bug: 213435093
Test: existing tests apply
Change-Id: Ic7a3a413d8e23c0405b4dd16f0b8c919a214eb32

core/java/com/android/internal/os/BinderLatencyObserver.java

@@ -19,7 +19,6 @@ package com.android.internal.os;
 import android.annotation.Nullable;
 import android.os.Binder;
 import android.os.Handler;
-import android.os.Looper;
 import android.os.SystemClock;
 import android.util.ArrayMap;
 import android.util.Slog;
@@ -181,7 +180,7 @@ public class BinderLatencyObserver {
         }
 
         public Handler getHandler() {
-            return new Handler(Looper.getMainLooper());
+            return BackgroundThread.getHandler();
         }
     }