ios: Use stl utilities from the base namespace

ios/chrome/browser/browser_state/chrome_browser_state_io_data.cc

Index: ios/chrome/browser/browser_state/chrome_browser_state_io_data.cc
diff --git a/ios/chrome/browser/browser_state/chrome_browser_state_io_data.cc b/ios/chrome/browser/browser_state/chrome_browser_state_io_data.cc
index 364f76d52e04ad1f8ca4b4457cd6ff96aa45a7f6..ce6bf8059bb6fda5f3f8f786c28c08abe86ded20 100644
--- a/ios/chrome/browser/browser_state/chrome_browser_state_io_data.cc
+++ b/ios/chrome/browser/browser_state/chrome_browser_state_io_data.cc
@@ -268,7 +268,7 @@ net::URLRequestContext* ChromeBrowserStateIOData::GetIsolatedAppRequestContext(
     const base::FilePath& partition_path) const {
   DCHECK(initialized_);
   AppRequestContext* context = nullptr;
-  if (ContainsKey(app_request_context_map_, partition_path)) {
+  if (base::ContainsKey(app_request_context_map_, partition_path)) {
     context = app_request_context_map_[partition_path];
   } else {
     context = AcquireIsolatedAppRequestContext(main_context);
@@ -281,7 +281,7 @@ net::URLRequestContext* ChromeBrowserStateIOData::GetIsolatedAppRequestContext(
 void ChromeBrowserStateIOData::SetCookieStoreForPartitionPath(
     std::unique_ptr<net::CookieStore> cookie_store,
     const base::FilePath& partition_path) {
-  DCHECK(ContainsKey(app_request_context_map_, partition_path));
+  DCHECK(base::ContainsKey(app_request_context_map_, partition_path));
   app_request_context_map_[partition_path]->SetCookieStore(
       std::move(cookie_store));
 }