Fix for 4080402 NPE in Transition.setDuration

Change-Id: I1e4499e3191beafdaf9bb4b7fd51798bd1eab300
diff --git a/media/java/android/media/videoeditor/Transition.java b/media/java/android/media/videoeditor/Transition.java
index 3e8fe94..fa9d26d 100755
--- a/media/java/android/media/videoeditor/Transition.java
+++ b/media/java/android/media/videoeditor/Transition.java
@@ -131,6 +131,11 @@
         if (durationMs > getMaximumDuration()) {
             throw new IllegalArgumentException("The duration is too large");
         }
+        if (afterMediaItem != null) {
+            mNativeHelper = afterMediaItem.getNativeContext();
+        }else {
+            mNativeHelper = beforeMediaItem.getNativeContext();
+        }
     }
 
     /**
diff --git a/media/java/android/media/videoeditor/TransitionAlpha.java b/media/java/android/media/videoeditor/TransitionAlpha.java
index f7d17cb..22788d4 100755
--- a/media/java/android/media/videoeditor/TransitionAlpha.java
+++ b/media/java/android/media/videoeditor/TransitionAlpha.java
@@ -104,13 +104,6 @@
         mWidth = dbo.outWidth;
         mHeight = dbo.outHeight;
 
-        if (afterMediaItem != null) {
-            mNativeHelper = afterMediaItem.getNativeContext();
-        }else {
-            mNativeHelper = beforeMediaItem.getNativeContext();
-        }
-
-
         mRGBMaskFile = String.format(mNativeHelper.getProjectPath() +
                 "/" + "mask" + transitionId+ ".rgb");