Add support to draw on texture.

Change-Id: I95dd5d29352692b702503969e1ebe07bc91a8a73
diff --git a/tests/src/com/android/gallery3d/ui/GLCanvasStub.java b/tests/src/com/android/gallery3d/ui/GLCanvasStub.java
index ee43cb9..5f749d8 100644
--- a/tests/src/com/android/gallery3d/ui/GLCanvasStub.java
+++ b/tests/src/com/android/gallery3d/ui/GLCanvasStub.java
@@ -80,4 +80,6 @@
     public void deleteRecycledResources() {}
     public void multiplyMatrix(float[] mMatrix, int offset) {}
     public void dumpStatisticsAndClear() {}
+    public void beginRenderTarget(RawTexture texture) {}
+    public void endRenderTarget() {}
 }