Remove CWV class and move setting User Agent to CWVWebViewConfiguration.

ios/web_view/internal/web_view_web_client.mm

Index: ios/web_view/internal/web_view_web_client.mm
diff --git a/ios/web_view/internal/web_view_web_client.mm b/ios/web_view/internal/web_view_web_client.mm
index a9c60a05d0ff75b889784b9d4d94aec7c0e5086e..2fcd5660696b449c8b768401bc17fcb368eaae61 100644
--- a/ios/web_view/internal/web_view_web_client.mm
+++ b/ios/web_view/internal/web_view_web_client.mm
@@ -15,8 +15,7 @@
 
 namespace ios_web_view {
 
-WebViewWebClient::WebViewWebClient(const std::string& user_agent_product)
-    : user_agent_product_(user_agent_product), web_main_parts_(nullptr) {}
+WebViewWebClient::WebViewWebClient() : web_main_parts_(nullptr) {}
 
 WebViewWebClient::~WebViewWebClient() = default;
 
@@ -25,14 +24,6 @@ web::WebMainParts* WebViewWebClient::CreateWebMainParts() {
   return web_main_parts_;
 }
 
-WebViewBrowserState* WebViewWebClient::browser_state() const {
-  return web_main_parts_->browser_state();
-}
-
-WebViewBrowserState* WebViewWebClient::off_the_record_browser_state() const {
-  return web_main_parts_->off_the_record_browser_state();
-}
-
 std::string WebViewWebClient::GetProduct() const {
   return user_agent_product_;
 }
@@ -47,4 +38,8 @@ NSString* WebViewWebClient::GetEarlyPageScript(
       .GetScript();
 }
 
+void WebViewWebClient::SetProduct(const std::string& user_agent_product) {
+  user_agent_product_ = user_agent_product;
+}
+
 }  // namespace ios_web_view