VR: Wire VrShell UI-related state to the scene manager.

chrome/browser/android/vr_shell/vr_browser_interface.h

 // 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.
 
 #ifndef CHROME_BROWSER_ANDROID_VR_SHELL_VR_BROWSER_INTERFACE_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_VR_BROWSER_INTERFACE_H_
 
 #include <memory>
 
 #include "base/android/jni_weak_ref.h"
 #include "base/bind.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "chrome/browser/android/vr_shell/ui_interface.h"
 #include "device/vr/android/gvr/gvr_gamepad_data_provider.h"
 #include "device/vr/vr_service.mojom.h"
 
 namespace blink {
 class WebInputEvent;
 }
 
 namespace vr_shell {
 
 // An interface for communication with Vr Browser. Many of the functions in this
 // interface are proxies to methods on VrShell.
 class VrBrowserInterface {
  public:
   virtual ~VrBrowserInterface() {}
 
-  virtual void ContentSurfaceChanged(jobject surface) {}
-  virtual void GvrDelegateReady() {}
-  virtual void UpdateGamepadData(device::GvrGamepadData) {}
-  virtual void AppButtonGesturePerformed(UiInterface::Direction direction) {}
-  virtual void OnAppButtonClicked() {}
+  virtual void ContentSurfaceChanged(jobject surface) = 0;
+  virtual void GvrDelegateReady() = 0;
+  virtual void UpdateGamepadData(device::GvrGamepadData) = 0;
+  virtual void AppButtonGesturePerformed(UiInterface::Direction direction) = 0;
+  virtual void AppButtonClicked() = 0;
   virtual void ProcessContentGesture(
-      std::unique_ptr<blink::WebInputEvent> event) {}
-  virtual void ForceExitVr() {}
+      std::unique_ptr<blink::WebInputEvent> event) = 0;
+  virtual void ForceExitVr() = 0;
   virtual void RunVRDisplayInfoCallback(
       const base::Callback<void(device::mojom::VRDisplayInfoPtr)>& callback,
-      device::mojom::VRDisplayInfoPtr* info) {}
-  virtual void OnContentPaused(bool enabled) {}
+      device::mojom::VRDisplayInfoPtr* info) = 0;
+  virtual void OnContentPaused(bool enabled) = 0;
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_VR_BROWSER_INTERFACE_H_