Created web::UserAgentType.

ios/web/public/navigation_item.h

Index: ios/web/public/navigation_item.h
diff --git a/ios/web/public/navigation_item.h b/ios/web/public/navigation_item.h
index 21024dcdb8bfd46b8ed0fb60d775dbdc9528e249..d528ee3350961436e82ffa97ee70414b61bfe494 100644
--- a/ios/web/public/navigation_item.h
+++ b/ios/web/public/navigation_item.h
@@ -10,6 +10,7 @@
 #include "base/strings/string16.h"
 #include "base/supports_user_data.h"
 #include "base/time/time.h"
+#import "ios/web/public/user_agent.h"
 #import "ios/web/public/web_state/page_display_state.h"
 #include "ui/base/page_transition_types.h"
 
@@ -108,10 +109,14 @@ class NavigationItem : public base::SupportsUserData {
   virtual void SetTimestamp(base::Time timestamp) = 0;
   virtual base::Time GetTimestamp() const = 0;
 
-  // |true| if this item uses a desktop user agent in HTTP requests and
-  // UIWebView.
-  virtual void SetIsOverridingUserAgent(bool is_overriding_user_agent) = 0;
-  virtual bool IsOverridingUserAgent() const = 0;
+  // The type of user agent requested for the navigation.  Setting this to a new
+  // value will reset the virtual URL of this NavigationItem to the original
+  // request URL because the final value of the URL is dependent on a page's
+  // implementation, which can potentially result in a different URL depending
+  // on the user agent (e.g. www.page.com may be reloaded as m.page.com for
+  // UserAgentType::MOBILE).
+  virtual void SetUserAgentType(UserAgentType type) = 0;

[Eugene But (OOO till 7-30), 2017/02/27 23:55:18]

Sorry, only now I realized that content has
SetIsOverridingUserAgent/GetIsOverridingUserAgent. The goal for ios/web is to be
similar to content where possible and ideally at some point we want to have the
same interfaces. This change is a move to the opposite direction. Can you talk
to content folks and ask if they like your changes? If so then we should change
both, content and web.

[kkhorimoto, 2017/03/01 18:29:25]

I've added a TODO to introduce the same change to content// since it's a bit out
of scope for this CL.  Landing this first will unblock Yuke's UA refactoring.

+  virtual UserAgentType GetUserAgentType() const = 0;
 
   // |true| if this item is the result of a POST request with data.
   virtual bool HasPostData() const = 0;