Raise priority of screenshot saving task

Bug: 157499085
Fix: 157499085
Test: manual
Change-Id: I71c9ff7809011f815a1854da367940616468055a

packages/SystemUI/src/com/android/systemui/screenshot/SaveImageInBackgroundTask.java

@@ -123,6 +123,7 @@ class SaveImageInBackgroundTask extends AsyncTask<Void, Void, Void> {
         if (isCancelled()) {
             return null;
         }
+        Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
 
         ContentResolver resolver = mContext.getContentResolver();
         Bitmap image = mParams.image;