Use SameDocument instead of SamePage term on iOS.

ios/web/web_state/web_state_impl.mm

Index: ios/web/web_state/web_state_impl.mm
diff --git a/ios/web/web_state/web_state_impl.mm b/ios/web/web_state/web_state_impl.mm
index 80364f53a2b782c8df092d0dd829151804e40433..83a2f1efbe5b44bd4f5deb7866910012113c3959 100644
--- a/ios/web/web_state/web_state_impl.mm
+++ b/ios/web/web_state/web_state_impl.mm
@@ -187,9 +187,9 @@ void WebStateImpl::OnNavigationCommitted(const GURL& url) {
     observer.DidFinishNavigation(context.get());
 }
 
-void WebStateImpl::OnSamePageNavigation(const GURL& url) {
+void WebStateImpl::OnSameDocumentNavigation(const GURL& url) {
   std::unique_ptr<NavigationContext> context =
-      NavigationContextImpl::CreateSamePageNavigationContext(this, url);
+      NavigationContextImpl::CreateSameDocumentNavigationContext(this, url);
   for (auto& observer : observers_)
     observer.DidFinishNavigation(context.get());
 }