Clean up WebVR RequestPresent and make callback asynchronous.

chrome/browser/android/vr_shell/vr_shell_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 CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_DELEGATE_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_DELEGATE_H_
 
 #include <jni.h>
 
 #include "base/android/jni_weak_ref.h"
@@ skipping 10 matching lines @@
 
 class VrShellDelegate : public device::GvrDelegateProvider {
  public:
   VrShellDelegate(JNIEnv* env, jobject obj);
   virtual ~VrShellDelegate();
 
   static VrShellDelegate* GetNativeDelegate(JNIEnv* env, jobject jdelegate);
 
   base::WeakPtr<device::GvrDeviceProvider> GetDeviceProvider();
 
-  // Called by the Java VrShellDelegate. Returns true if the GvrDeviceProvider
-  // needs to handle shutdown first.
-  void ExitWebVRIfNecessary(JNIEnv* env, jobject obj);
+  void SetPresentResult(JNIEnv* env, jobject obj, jboolean result);
 
   // device::GvrDelegateProvider implementation
-  bool RequestWebVRPresent(
-      base::WeakPtr<device::GvrDeviceProvider> device_provider) override;
+  void RequestWebVRPresent(
+      base::WeakPtr<device::GvrDeviceProvider> device_provider,
+      const base::Callback<void(bool)>& callback) override;
   void ExitWebVRPresent() override;
   base::WeakPtr<device::GvrDelegate> GetNonPresentingDelegate() override;
   void DestroyNonPresentingDelegate() override;
 
  private:
   std::unique_ptr<device::GvrDelegate> non_presenting_delegate_;
   base::android::ScopedJavaGlobalRef<jobject> j_vr_shell_delegate_;
   base::WeakPtr<device::GvrDeviceProvider> device_provider_;
+  base::Callback<void(bool)> present_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(VrShellDelegate);
 };
 
 bool RegisterVrShellDelegate(JNIEnv* env);
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_DELEGATE_H_