Created web::UserAgentType.

ios/web/navigation/navigation_item_impl.mm

Index: ios/web/navigation/navigation_item_impl.mm
diff --git a/ios/web/navigation/navigation_item_impl.mm b/ios/web/navigation/navigation_item_impl.mm
index 31f357566080a0b3b5613312130691500edc34bc..7e682a9d733c8f368cd60edf1743f91905d0954f 100644
--- a/ios/web/navigation/navigation_item_impl.mm
+++ b/ios/web/navigation/navigation_item_impl.mm
@@ -12,6 +12,7 @@
 #include "base/logging.h"
 #include "components/url_formatter/url_formatter.h"
 #import "ios/web/navigation/navigation_manager_impl.h"
+#import "ios/web/public/web_client.h"
 #include "ui/base/page_transition_types.h"
 #include "ui/gfx/text_elider.h"
 
@@ -40,7 +41,7 @@ static int GetUniqueIDInConstructor() {
 NavigationItemImpl::NavigationItemImpl()
     : unique_id_(GetUniqueIDInConstructor()),
       transition_type_(ui::PAGE_TRANSITION_LINK),
-      is_overriding_user_agent_(false),
+      user_agent_type_(UserAgentType::MOBILE),
       is_created_from_push_state_(false),
       has_state_been_replaced_(false),
       is_created_from_hash_change_(false),
@@ -64,7 +65,7 @@ static int GetUniqueIDInConstructor() {
       favicon_(item.favicon_),
       ssl_(item.ssl_),
       timestamp_(item.timestamp_),
-      is_overriding_user_agent_(item.is_overriding_user_agent_),
+      user_agent_type_(item.user_agent_type_),
       http_request_headers_([item.http_request_headers_ copy]),
       serialized_state_object_([item.serialized_state_object_ copy]),
       is_created_from_push_state_(item.is_created_from_push_state_),
@@ -206,13 +207,14 @@ static int GetUniqueIDInConstructor() {
   return timestamp_;
 }
 
-void NavigationItemImpl::SetIsOverridingUserAgent(
-    bool is_overriding_user_agent) {
-  is_overriding_user_agent_ = is_overriding_user_agent;
+void NavigationItemImpl::SetUserAgentType(UserAgentType type) {
+  user_agent_type_ = type;
+  DCHECK_EQ(GetWebClient()->IsAppSpecificURL(GetVirtualURL()),
+            user_agent_type_ == UserAgentType::NONE);
 }
 
-bool NavigationItemImpl::IsOverridingUserAgent() const {
-  return is_overriding_user_agent_;
+UserAgentType NavigationItemImpl::GetUserAgentType() const {
+  return user_agent_type_;
 }
 
 bool NavigationItemImpl::HasPostData() const {