Implement request mobile site.

ios/chrome/browser/tabs/tab.mm

Index: ios/chrome/browser/tabs/tab.mm
diff --git a/ios/chrome/browser/tabs/tab.mm b/ios/chrome/browser/tabs/tab.mm
index 3b94a7e5f17d072ce6a37b4b3b194c18548b963c..29e6c97cf7639d70992406f2fda3314575ef1aa7 100644
--- a/ios/chrome/browser/tabs/tab.mm
+++ b/ios/chrome/browser/tabs/tab.mm
@@ -198,6 +198,15 @@ bool IsApplicationStateNotActive(UIApplicationState state) {
           state == UIApplicationStateInactive);
 }
 
+// Returns true if |item| is the result of a HTTP redirect.
+// Returns false if |item| is nullptr;
+bool IsItemRedirectItem(web::NavigationItem* item) {
+  if (!item)
+    return false;
+
+  return (ui::PageTransition::PAGE_TRANSITION_IS_REDIRECT_MASK &
+          item->GetTransitionType()) == 0;
+}
 }  // namespace
 
 @interface Tab ()<CRWWebStateObserver,
@@ -1358,7 +1367,7 @@ - (BOOL)usesDesktopUserAgent {
          visibleItem->GetUserAgentType() == web::UserAgentType::DESKTOP;
 }
 
-- (void)reloadForDesktopUserAgent {
+- (void)reloadWithUserAgentType:(web::UserAgentType)userAgentType {
   // This removes the web view, which will be recreated at the end of this.
   [self.webController requirePageReconstruction];
 
@@ -1367,25 +1376,41 @@ - (void)reloadForDesktopUserAgent {
   // navigation from new navigations.
   web::NavigationManager* navigationManager = [self navigationManager];
   DCHECK(navigationManager);
-  web::NavigationItem* lastNonRedirectedItem =
-      GetLastCommittedNonRedirectedItem(navigationManager);
-  if (!lastNonRedirectedItem)
+
+  web::NavigationItem* lastNonRedirectItem =
+      navigationManager->GetTransientItem();
+  if (!lastNonRedirectItem || IsItemRedirectItem(lastNonRedirectItem))
+    lastNonRedirectItem = navigationManager->GetVisibleItem();
+  if (!lastNonRedirectItem || IsItemRedirectItem(lastNonRedirectItem))
+    lastNonRedirectItem = GetLastCommittedNonRedirectedItem(navigationManager);
+
+  if (!lastNonRedirectItem)
     return;
 
   // |reloadURL| will be empty if a page was open by DOM.
-  GURL reloadURL(lastNonRedirectedItem->GetOriginalRequestURL());
+  GURL reloadURL(lastNonRedirectItem->GetOriginalRequestURL());
   if (reloadURL.is_empty()) {
     DCHECK(self.webState && self.webState->HasOpener());
-    reloadURL = lastNonRedirectedItem->GetVirtualURL();
+    reloadURL = lastNonRedirectItem->GetVirtualURL();
   }
 
   web::NavigationManager::WebLoadParams params(reloadURL);
-  params.referrer = lastNonRedirectedItem->GetReferrer();
-  // A new navigation is needed here for reloading with desktop User-Agent.
-  params.user_agent_override_option =
-      web::NavigationManager::UserAgentOverrideOption::DESKTOP;
-  params.transition_type =
-      ui::PageTransitionFromInt(ui::PAGE_TRANSITION_FORM_SUBMIT);
+  params.referrer = lastNonRedirectItem->GetReferrer();
+  params.transition_type = ui::PAGE_TRANSITION_RELOAD;
+
+  switch (userAgentType) {
+    case web::UserAgentType::DESKTOP:
+      params.user_agent_override_option =
+          web::NavigationManager::UserAgentOverrideOption::DESKTOP;
+      break;
+    case web::UserAgentType::MOBILE:
+      params.user_agent_override_option =
+          web::NavigationManager::UserAgentOverrideOption::MOBILE;
+      break;
+    case web::UserAgentType::NONE:
+      NOTREACHED();
+  }
+
   navigationManager->LoadURLWithParams(params);
 }