VrShell: Exit fullscreen on app button press.

chrome/browser/android/vr_shell/vr_gl_thread.h

 // Copyright 2016 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.
 
 #ifndef CHROME_BROWSER_ANDROID_VR_SHELL_VR_GL_THREAD_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_VR_GL_THREAD_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 33 matching lines @@
   // VrBrowserInterface implementation (VrShellGl calling to UI and VrShell).
   void ContentSurfaceChanged(jobject surface) override;
   void GvrDelegateReady() override;
   void UpdateGamepadData(device::GvrGamepadData) override;
   void AppButtonClicked() override;
   void AppButtonGesturePerformed(UiInterface::Direction direction) override;
   void ProcessContentGesture(
       std::unique_ptr<blink::WebInputEvent> event) override;
   void ForceExitVr() override;
   void ExitPresent() override;
+  void ExitFullscreen() override;
   void RunVRDisplayInfoCallback(
       const base::Callback<void(device::mojom::VRDisplayInfoPtr)>& callback,
       device::mojom::VRDisplayInfoPtr* info) override;
   void OnContentPaused(bool enabled) override;
   void NavigateBack() override;
 
   // UiInterface implementation (VrShell calling to the UI).
   void SetFullscreen(bool enabled) override;
   void SetHistoryButtonsEnabled(bool can_go_back, bool can_go_forward) override;
   void SetLoadProgress(double progress) override;
@@ skipping 22 matching lines @@
   bool initially_web_vr_;
   bool in_cct_;
   bool reprojected_rendering_;
 
   DISALLOW_COPY_AND_ASSIGN(VrGLThread);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_VR_GL_THREAD_H_