Do not enter touch mode on non-touchscreen events

Currently ACTION_DOWN and ACTION_SCROLL cause
entering touch mode regardless of the event source.
This is especially awkward for mouse.

This should only happen when the event source is
SOURCE_TOUCHSCREEN.

Bug: 35314124
Test: android.cts.view.ViewTest#testTouchMode
Change-Id: I2205d4240be4afcbd9a3ac5558e701f7cac51926

core/java/android/view/ViewRootImpl.java

@@ -4279,7 +4279,8 @@ public final class ViewRootImpl implements ViewParent,
 
             // Enter touch mode on down or scroll.
             final int action = event.getAction();
-            if (action == MotionEvent.ACTION_DOWN || action == MotionEvent.ACTION_SCROLL) {
+            if (event.isFromSource(InputDevice.SOURCE_TOUCHSCREEN)
+                    && (action == MotionEvent.ACTION_DOWN || action == MotionEvent.ACTION_SCROLL)) {
                 ensureTouchMode(true);
             }