Get transform matrix relative to parent coordinate space

There was an issue where we were getting it w.r.t screen
as opposed to parent.

Author: Kaushik Iska

shell/platform/android/io/flutter/embedding/engine/mutatorsstack/FlutterMutatorView.java

@@ -5,7 +5,9 @@
 import android.graphics.Canvas;
 import android.graphics.Matrix;
 import android.graphics.Path;
+import android.graphics.Rect;
 import android.view.MotionEvent;
+import android.view.ViewGroup;
 import android.widget.FrameLayout;
 import androidx.annotation.NonNull;
 import io.flutter.embedding.android.AndroidTouchProcessor;
@@ -122,10 +124,17 @@ public boolean onTouchEvent(MotionEvent event) {
       return super.onTouchEvent(event);
     }
 
+    // get the offset relative to parent.
+    Rect offset = new Rect();
+    getDrawingRect(offset);
+
+    ViewGroup parentViewGroup = (ViewGroup) getParent();
+    parentViewGroup.offsetDescendantRectToMyCoords(this, offset);
+
     // Mutator view itself doesn't rotate, scale, skew, etc.
     // we only need to account for translation.
     Matrix screenMatrix = new Matrix();
-    screenMatrix.postTranslate(getLeft(), getTop());
+    screenMatrix.postTranslate(offset.left, offset.top);
 
     return androidTouchProcessor.onTouchEvent(event, screenMatrix);
   }