Clean up some VrShell threading issues and remove unnecessary WeakPtr types.

device/vr/android/gvr/gvr_device.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_DEVICE_H
 #define DEVICE_VR_ANDROID_GVR_DEVICE_H
 
 #include "base/macros.h"
-#include "base/memory/weak_ptr.h"
 #include "device/vr/vr_device.h"
 
 namespace gvr {
 class GvrApi;
 }  // namespace gvr
 
 namespace device {
 
 class GvrDeviceProvider;
 class GvrDelegate;
 
 class GvrDevice : public VRDevice {
  public:
-  GvrDevice(GvrDeviceProvider* provider,
-            const base::WeakPtr<GvrDelegate>& delegate);
+  GvrDevice(GvrDeviceProvider* provider, GvrDelegate* delegate);
   ~GvrDevice() override;
 
   // VRDevice
   mojom::VRDisplayInfoPtr GetVRDevice() override;
   mojom::VRPosePtr GetPose() override;
   void ResetPose() override;
 
   void RequestPresent(const base::Callback<void(bool)>& callback) override;
   void SetSecureOrigin(bool secure_origin) override;
   void ExitPresent() override;
 
   void SubmitFrame(mojom::VRPosePtr pose) override;
   void UpdateLayerBounds(mojom::VRLayerBoundsPtr left_bounds,
                          mojom::VRLayerBoundsPtr right_bounds) override;
 
-  void SetDelegate(const base::WeakPtr<GvrDelegate>& delegate);
+  void SetDelegate(GvrDelegate* delegate);
 
  private:
   gvr::GvrApi* GetGvrApi();
 
-  base::WeakPtr<GvrDelegate> delegate_;
+  GvrDelegate* delegate_;
   GvrDeviceProvider* gvr_provider_;
   bool secure_origin_ = false;
   uint32_t pose_index_ = 1;
 
   DISALLOW_COPY_AND_ASSIGN(GvrDevice);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_VR_ANDROID_GVR_DEVICE_H