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

device/vr/android/gvr/gvr_device.h

Index: device/vr/android/gvr/gvr_device.h
diff --git a/device/vr/android/gvr/gvr_device.h b/device/vr/android/gvr/gvr_device.h
index f1f0f4e13db10263b84c4c441093aaab8e105a58..4d57f581a64d2dab47c4978a4c6601f2379634eb 100644
--- a/device/vr/android/gvr/gvr_device.h
+++ b/device/vr/android/gvr/gvr_device.h
@@ -6,7 +6,6 @@
 #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 {
@@ -20,8 +19,7 @@ class GvrDelegate;
 
 class GvrDevice : public VRDevice {
  public:
-  GvrDevice(GvrDeviceProvider* provider,
-            const base::WeakPtr<GvrDelegate>& delegate);
+  GvrDevice(GvrDeviceProvider* provider, GvrDelegate* delegate);
   ~GvrDevice() override;
 
   // VRDevice
@@ -37,12 +35,12 @@ class GvrDevice : public VRDevice {
   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;