Convert //ios from scoped_ptr to std::unique_ptr.

ios/web/interstitials/native_web_interstitial_impl.h

Index: ios/web/interstitials/native_web_interstitial_impl.h
diff --git a/ios/web/interstitials/native_web_interstitial_impl.h b/ios/web/interstitials/native_web_interstitial_impl.h
index 1280ef497933c87207fd98ea359c961fd2dc55a4..4a9d4f4a1efaf6138375ff857ca038cbf0f7e214 100644
--- a/ios/web/interstitials/native_web_interstitial_impl.h
+++ b/ios/web/interstitials/native_web_interstitial_impl.h
@@ -7,6 +7,8 @@
 
 #include "ios/web/interstitials/web_interstitial_impl.h"
 
+#include <memory>
+
 #include "base/ios/weak_nsobject.h"
 #include "base/mac/scoped_nsobject.h"
 
@@ -18,10 +20,11 @@ class NativeWebInterstitialDelegate;
 // interstitials created via native views.
 class NativeWebInterstitialImpl : public WebInterstitialImpl {
  public:
-  NativeWebInterstitialImpl(WebStateImpl* web_state,
-                            bool new_navigation,
-                            const GURL& url,
-                            scoped_ptr<NativeWebInterstitialDelegate> delegate);
+  NativeWebInterstitialImpl(
+      WebStateImpl* web_state,
+      bool new_navigation,
+      const GURL& url,
+      std::unique_ptr<NativeWebInterstitialDelegate> delegate);
   ~NativeWebInterstitialImpl() override;
 
   // WebInterstitialImpl implementation:
@@ -36,7 +39,7 @@ class NativeWebInterstitialImpl : public WebInterstitialImpl {
 
  private:
   // The native interstitial delegate.
-  scoped_ptr<NativeWebInterstitialDelegate> delegate_;
+  std::unique_ptr<NativeWebInterstitialDelegate> delegate_;
   // The transient content view containing interstitial content.
   base::scoped_nsobject<CRWContentView> content_view_;
 };