Clean up WebVR RequestPresent and make callback asynchronous.

device/vr/android/gvr/gvr_delegate.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 DEVICE_VR_ANDROID_GVR_DELEGATE_H
 #define DEVICE_VR_ANDROID_GVR_DELEGATE_H
 
 #include "base/memory/weak_ptr.h"
 #include "device/vr/android/gvr/gvr_device_provider.h"
 #include "device/vr/vr_export.h"
@@ skipping 19 matching lines @@
   virtual gvr::Sizei GetWebVRCompositorSurfaceSize() = 0;
   virtual void SetWebVRRenderSurfaceSize(int width, int height) = 0;
   virtual gvr::GvrApi* gvr_api() = 0;
 };
 
 class DEVICE_VR_EXPORT GvrDelegateProvider {
  public:
   static void SetInstance(GvrDelegateProvider* delegate_provider);
   static GvrDelegateProvider* GetInstance();
 
-  virtual bool RequestWebVRPresent(
-      base::WeakPtr<GvrDeviceProvider> device_provider) = 0;
+  virtual void RequestWebVRPresent(
+      base::WeakPtr<GvrDeviceProvider> device_provider,
+      const base::Callback<void(bool)>& callback) = 0;
   virtual void ExitWebVRPresent() = 0;
   virtual base::WeakPtr<GvrDelegate> GetNonPresentingDelegate() = 0;
   virtual void DestroyNonPresentingDelegate() = 0;
 
  private:
   static GvrDelegateProvider* delegate_provider_;
 };
 
 }  // namespace device
 
 #endif  // DEVICE_VR_ANDROID_GVR_DELEGATE_H