[iOS] Refactoring web CRWSessionController user agent code.

ios/web/public/test/fakes/test_navigation_manager.mm

Index: ios/web/public/test/fakes/test_navigation_manager.mm
diff --git a/ios/web/public/test/fakes/test_navigation_manager.mm b/ios/web/public/test/fakes/test_navigation_manager.mm
index 38eafcac63a99ee49af5d57b60ac6610730bff3e..954d59afa2bccb5c7c6f0ec68f7bdb49884ca61f 100644
--- a/ios/web/public/test/fakes/test_navigation_manager.mm
+++ b/ios/web/public/test/fakes/test_navigation_manager.mm
@@ -54,24 +54,20 @@
 
 void TestNavigationManager::DiscardNonCommittedItems() {
   NOTREACHED();
-  return;
 }
 
 void TestNavigationManager::LoadIfNecessary() {
   NOTREACHED();
-  return;
 }
 
 void TestNavigationManager::LoadURLWithParams(
     const NavigationManager::WebLoadParams& params) {
   NOTREACHED();
-  return;
 }
 
 void TestNavigationManager::AddTransientURLRewriter(
     BrowserURLRewriter::URLRewriter rewriter) {
   NOTREACHED();
-  return;
 }
 
 int TestNavigationManager::GetItemCount() const {
@@ -121,22 +117,22 @@
 
 void TestNavigationManager::GoBack() {
   NOTREACHED();
-  return;
 }
 
 void TestNavigationManager::GoForward() {
   NOTREACHED();
-  return;
 }
 
 void TestNavigationManager::GoToIndex(int index) {
   NOTREACHED();
-  return;
 }
 
 void TestNavigationManager::Reload(bool check_for_repost) {
   NOTREACHED();
-  return;
+}
+
+void TestNavigationManager::OverrideDesktopUserAgentForNextPendingItem() {
+  NOTREACHED();
 }
 
 }  // namespace web