Add setTextAsync method to TextView

This CL adds a setTextAsync method to the TextView class. This method allows the text to be maniputed on a background thread and set the result on main thread with Runnable.

Bug: 289250881
Test: Manual by checking Notification and Widget Texts.
Change-Id: I3d74f2de2503318441c868bb931a2bc447c03517

core/java/android/widget/TextView.java

@@ -6938,11 +6938,25 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
      *                                  parameters used to create the PrecomputedText mismatches
      *                                  with this TextView.
      */
-    @android.view.RemotableViewMethod
+    @android.view.RemotableViewMethod(asyncImpl = "setTextAsync")
     public final void setText(CharSequence text) {
         setText(text, mBufferType);
     }
 
+    /**
+     * RemotableViewMethod's asyncImpl of {@link #setText(CharSequence)}.
+     * This should be called on a background thread, and returns a Runnable which is then must be
+     * called on the main thread to complete the operation and set text.
+     * @param text text to be displayed
+     * @return Runnable that sets text; must be called on the main thread by the caller of this
+     * method to complete the operation
+     * @hide
+     */
+    @NonNull
+    public Runnable setTextAsync(@Nullable CharSequence text) {
+        return () -> setText(text);
+    }
+
     /**
      * Sets the text to be displayed but retains the cursor position. Same as
      * {@link #setText(CharSequence)} except that the cursor position (if any) is retained in the