[vr] Close exit prompt when clicking on background

chrome/browser/android/vr_shell/ui_elements/exit_prompt_backplane.cc

Index: chrome/browser/android/vr_shell/ui_elements/exit_prompt_backplane.cc
diff --git a/chrome/browser/android/vr_shell/ui_elements/exit_prompt_backplane.cc b/chrome/browser/android/vr_shell/ui_elements/exit_prompt_backplane.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6dcd5a834b64feec1350c0bee69498501a9a1fe8
--- /dev/null
+++ b/chrome/browser/android/vr_shell/ui_elements/exit_prompt_backplane.cc
@@ -0,0 +1,25 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/android/vr_shell/ui_elements/exit_prompt_backplane.h"
+
+#include "base/memory/ptr_util.h"
+
+namespace vr_shell {
+
+ExitPromptBackplane::ExitPromptBackplane(
+    const base::Callback<void()>& click_callback)
+    : click_callback_(click_callback) {}
+
+ExitPromptBackplane::~ExitPromptBackplane() = default;
+
+void ExitPromptBackplane::OnButtonUp(const gfx::PointF& position) {
+  // We always run the callback. That is, if the user clicks the controller
+  // button on the backplane and releases it on another element in front of the
+  // backplane, this callback will still be called. Elements are input locked
+  // on button down and it's probably not worth special-casing the backplane.
+  click_callback_.Run();
+}
+
+}  // namespace vr_shell