Add CLASSIFICATION_TWO_FINGER_SCROLL for touchpad scrolling

This will be used to denote the single-finger touches that
TouchInputMapper creates to simulate scrolling when the user makes
two-finger swipes on the touchpad.

Bug: 246758376
Test: check new value is sent to a test app when scrolling on a touchpad
Change-Id: Id93cba764522e36d850f7013ab8a117f64716fac

core/api/current.txt

@@ -49222,6 +49222,7 @@ package android.view {
     field public static final int CLASSIFICATION_AMBIGUOUS_GESTURE = 1; // 0x1
     field public static final int CLASSIFICATION_DEEP_PRESS = 2; // 0x2
     field public static final int CLASSIFICATION_NONE = 0; // 0x0
+    field public static final int CLASSIFICATION_TWO_FINGER_SWIPE = 3; // 0x3
     field @NonNull public static final android.os.Parcelable.Creator<android.view.MotionEvent> CREATOR;
     field public static final int EDGE_BOTTOM = 2; // 0x2
     field public static final int EDGE_LEFT = 4; // 0x4

core/java/android/view/MotionEvent.java

@@ -1457,10 +1457,20 @@ public final class MotionEvent extends InputEvent implements Parcelable {
      */
     public static final int CLASSIFICATION_DEEP_PRESS = 2;
 
+    /**
+     * Classification constant: touchpad scroll.
+     *
+     * The current event stream represents the user scrolling with two fingers on a touchpad.
+     *
+     * @see #getClassification
+     */
+    public static final int CLASSIFICATION_TWO_FINGER_SWIPE = 3;
+
     /** @hide */
     @Retention(SOURCE)
     @IntDef(prefix = { "CLASSIFICATION" }, value = {
-            CLASSIFICATION_NONE, CLASSIFICATION_AMBIGUOUS_GESTURE, CLASSIFICATION_DEEP_PRESS})
+            CLASSIFICATION_NONE, CLASSIFICATION_AMBIGUOUS_GESTURE, CLASSIFICATION_DEEP_PRESS,
+            CLASSIFICATION_TWO_FINGER_SWIPE})
     public @interface Classification {};
 
     /**
@@ -3862,9 +3872,11 @@ public final class MotionEvent extends InputEvent implements Parcelable {
                 return "AMBIGUOUS_GESTURE";
             case CLASSIFICATION_DEEP_PRESS:
                 return "DEEP_PRESS";
+            case CLASSIFICATION_TWO_FINGER_SWIPE:
+                return "TWO_FINGER_SWIPE";
 
         }
-        return "NONE";
+        return "UNKNOWN";
     }
 
     /**

native/android/input.cpp

@@ -295,6 +295,8 @@ int32_t AMotionEvent_getClassification(const AInputEvent* motion_event) {
             return AMOTION_EVENT_CLASSIFICATION_AMBIGUOUS_GESTURE;
         case android::MotionClassification::DEEP_PRESS:
             return AMOTION_EVENT_CLASSIFICATION_DEEP_PRESS;
+        case android::MotionClassification::TWO_FINGER_SWIPE:
+            return AMOTION_EVENT_CLASSIFICATION_TWO_FINGER_SWIPE;
     }
 }