Cleanup VulkanWindowContext for use on Android

tools/viewer/sk_app/android/Window_android.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 Window_android_DEFINED
 #define Window_android_DEFINED
 
-#include <android/native_window_jni.h>
-
 #include "../Window.h"
+#include "WindowContext_android.h"
 #include "surface_glue_android.h"
 
 namespace sk_app {
 
-struct ContextPlatformData_android {
-    ANativeWindow* fNativeWindow;
-};
-
 class Window_android : public Window {
 public:
     Window_android() : Window() {}
     ~Window_android() override {}
 
     bool init(SkiaAndroidApp* skiaAndroidApp);
     void initDisplay(ANativeWindow* window);
     void onDisplayDestroyed();
 
     const DisplayParams& getDisplayParams() override;
@@ skipping 14 matching lines @@
 private:
     SkiaAndroidApp* fSkiaAndroidApp = nullptr;
     SkRect fContentRect;
     DisplayParams fDisplayParams;
     BackendType fBackendType;
 };
 
 }   // namespace sk_app
 
 #endif