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

chrome/browser/android/vr_shell/vr_shell_delegate.h

Index: chrome/browser/android/vr_shell/vr_shell_delegate.h
diff --git a/chrome/browser/android/vr_shell/vr_shell_delegate.h b/chrome/browser/android/vr_shell/vr_shell_delegate.h
index 97bf2bb8ea5456ffc91961836b825330d798458b..3731bb2f7972489e448db590fe0c1d245c7dc6e3 100644
--- a/chrome/browser/android/vr_shell/vr_shell_delegate.h
+++ b/chrome/browser/android/vr_shell/vr_shell_delegate.h
@@ -24,28 +24,28 @@ class VrShellDelegate : public device::GvrDelegateProvider {
 
   static VrShellDelegate* GetNativeDelegate(JNIEnv* env, jobject jdelegate);
 
-  void SetDelegate(const base::WeakPtr<device::GvrDelegate>& delegate);
+  void SetDelegate(device::GvrDelegate* delegate);
   void RemoveDelegate();
 
   void SetPresentResult(JNIEnv* env, jobject obj, jboolean result);
   void DisplayActivate(JNIEnv* env, jobject obj);
 
   void ForceExitVr();
+  device::GvrDeviceProvider* device_provider() { return device_provider_; }
 
   // device::GvrDelegateProvider implementation
-  void SetDeviceProvider(
-      base::WeakPtr<device::GvrDeviceProvider> device_provider) override;
+  void SetDeviceProvider(device::GvrDeviceProvider* device_provider) override;
   void RequestWebVRPresent(const base::Callback<void(bool)>& callback) override;
   void ExitWebVRPresent() override;
-  base::WeakPtr<device::GvrDelegate> GetNonPresentingDelegate() override;
+  device::GvrDelegate* GetNonPresentingDelegate() override;
   void DestroyNonPresentingDelegate() override;
   void SetListeningForActivate(bool listening) 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::WeakPtr<device::GvrDelegate> delegate_;
+  device::GvrDeviceProvider* device_provider_ = nullptr;
+  device::GvrDelegate* delegate_ = nullptr;
   base::Callback<void(bool)> present_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(VrShellDelegate);