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..ef446c18f31f0cb7c55fe552bbac43248cf23e1f 100644
--- a/ios/web/interstitials/native_web_interstitial_impl.h
+++ b/ios/web/interstitials/native_web_interstitial_impl.h
@@ -18,10 +18,11 @@ 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 +37,7 @@ 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_;
 };