Create a drag shadow surface in app process,

Previoulsy a drag shadow surface is created in the system process. App needs
to call one more binder call (prepareDrag) to obtain the surface from
the system process.

The CL lets an app to create a drag shadow surface by itself. Then app
transfer the surface to system server by using reparent
API.

Bug: 70818582
Test: com.android.server.wm.DragDropControllerTests,
      android.server.wm.CrossAppDragAndDropTests,
      manually check the drag and drop behavior on test app.
Change-Id: I72796efffbefe78a802d7c441dea308d1cdea572
diff --git a/services/tests/servicestests/src/com/android/server/wm/DragDropControllerTests.java b/services/tests/servicestests/src/com/android/server/wm/DragDropControllerTests.java
index ac29163..9a0d400 100644
--- a/services/tests/servicestests/src/com/android/server/wm/DragDropControllerTests.java
+++ b/services/tests/servicestests/src/com/android/server/wm/DragDropControllerTests.java
@@ -28,6 +28,7 @@
 import static org.mockito.Mockito.when;
 
 import android.content.ClipData;
+import android.graphics.PixelFormat;
 import android.os.IBinder;
 import android.os.Looper;
 import android.os.UserHandle;
@@ -37,6 +38,7 @@
 import android.support.test.runner.AndroidJUnit4;
 import android.view.InputChannel;
 import android.view.Surface;
+import android.view.SurfaceControl;
 import android.view.SurfaceSession;
 import android.view.View;
 import com.android.internal.annotations.GuardedBy;
@@ -147,9 +149,7 @@
 
     @Test
     public void testPrepareDrag_ZeroSizeSurface() throws Exception {
-        final Surface surface = new Surface();
-        mToken = mTarget.prepareDrag(
-                new SurfaceSession(), 0, 0, mWindow.mClient, 0, 0, 0, surface);
+        mToken = mTarget.prepareDrag(new SurfaceSession(), 0, 0, mWindow.mClient, 0, 0, 0);
         assertNull(mToken);
     }
 
@@ -169,16 +169,24 @@
     }
 
     private void dragFlow(int flag, ClipData data, float dropX, float dropY) {
-        final Surface surface = new Surface();
-        mToken = mTarget.prepareDrag(
-                new SurfaceSession(), 0, 0, mWindow.mClient, flag, 100, 100, surface);
+        mToken = mTarget.prepareDrag(new SurfaceSession(), 0, 0, mWindow.mClient, flag, 100, 100);
         assertNotNull(mToken);
+        final SurfaceSession appSession = new SurfaceSession();
+        try {
+            final SurfaceControl surface = new SurfaceControl.Builder(appSession)
+                    .setName("drag surface")
+                    .setSize(100, 100)
+                    .setFormat(PixelFormat.TRANSLUCENT)
+                    .build();
 
-        assertTrue(sWm.mInputManager.transferTouchFocus(null, null));
-        assertTrue(mTarget.performDrag(
-                mWindow.mClient, mToken, 0, 0, 0, 0, 0, data));
+            assertTrue(sWm.mInputManager.transferTouchFocus(null, null));
+            assertNotNull(mTarget.performDrag(
+                    new SurfaceSession(), mWindow.mClient, mToken, surface, 0, 0, 0, 0, 0, data));
 
-        mTarget.handleMotionEvent(false, dropX, dropY);
-        mToken = mWindow.mClient.asBinder();
+            mTarget.handleMotionEvent(false, dropX, dropY);
+            mToken = mWindow.mClient.asBinder();
+        } finally {
+            appSession.kill();
+        }
     }
 }