[vr] fix vr_testapp compilation

This change contains updates to the test app to cope with interface
changes introduced in crrev.com/c/1147754.

Bug: None
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:linux_vr;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: Ia2491fd96819ba2f4fc95ab2cbaec2aedcee05f5
Reviewed-on: https://chromium-review.googlesource.com/1155003Reviewed-by: Christopher Grant <cjgrant@chromium.org>
Commit-Queue: Ian Vollick <vollick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579057}

chrome/browser/vr/testapp/vr_testapp.cc

@@ -139,13 +139,11 @@ class AppWindow : public ui::PlatformWindowDelegate {
   void OnClosed() override {}
   void OnWindowStateChanged(ui::PlatformWindowState new_state) override {}
   void OnLostCapture() override {}
-  void OnAcceleratedWidgetAvailable(gfx::AcceleratedWidget widget,
-                                    float device_pixel_ratio) override {
+  void OnAcceleratedWidgetAvailable(gfx::AcceleratedWidget widget) override {
     DCHECK_NE(widget, gfx::kNullAcceleratedWidget);
     widget_ = widget;
   }
   void OnAcceleratedWidgetDestroyed() override { NOTREACHED(); }
-  void OnAcceleratedWidgetDestroying() override { NOTREACHED(); }
   void OnActivationChanged(bool active) override {}
 
  private: