Cleanup VulkanWindowContext for use on Android

tools/viewer/Viewer.h

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #ifndef Viewer_DEFINED
 #define Viewer_DEFINED
 
 #include "sk_app/Application.h"
 #include "sk_app/CommandSet.h"
 #include "sk_app/Window.h"
 #include "gm.h"
 #include "SkAnimTimer.h"
+#include "SkTouchGesture.h"
 #include "Slide.h"
 
 class SkCanvas;
 
 class Viewer : public sk_app::Application {
 public:
     Viewer(int argc, char** argv, void* platformData);
     ~Viewer() override;
 
     void onPaint(SkCanvas* canvas);
@@ skipping 39 matching lines @@
 
     // identity unless the window initially scales the content to fit the screen.
     SkMatrix               fDefaultMatrix;
     SkMatrix               fDefaultMatrixInv;
 
     Json::Value            fAllSlideNames; // cache all slide names for fast updateUIState
 };
 
 
 #endif