Remove request group ID from UA with WKWebView

Without the network stack, there is no need to append a request group
ID to the user agent. This removes it in a minimal way; once the
WKWebView-with-network-stack config is removed it'll be easier to
clean up the cruft.

BUG=None

Review URL: https://codereview.chromium.org/1310763002

Cr-Commit-Position: refs/heads/master@{#345078}

2 files changed, 3 insertions, 0 deletions

diff --git a/ios/web/net/request_group_util.h b/ios/web/net/request_group_util.h
index 525f2d0..071f51f 100644
--- a/ios/web/net/request_group_util.h
+++ b/ios/web/net/request_group_util.h
@@ -30,6 +30,7 @@ NSString* ExtractRequestGroupIDFromUserAgent(NSString* user_agent);
 // Returns a new user agent, which is the result of the encoding of
 // |request_group_id| in |base_user_agent|. The request group ID can be later
 // extracted with ExtractRequestGroupIDFromUserAgent().
+// If request_group_id is nil, returns base_user_agent.
 NSString* AddRequestGroupIDToUserAgent(NSString* base_user_agent,
                                        NSString* request_group_id);
 
diff --git a/ios/web/net/request_group_util.mm b/ios/web/net/request_group_util.mm
index 9a41cef..5aecb10 100644
--- a/ios/web/net/request_group_util.mm
+++ b/ios/web/net/request_group_util.mm
@@ -65,6 +65,8 @@ NSString* ExtractRequestGroupIDFromUserAgent(NSString* user_agent) {
 
 NSString* AddRequestGroupIDToUserAgent(NSString* base_user_agent,
                                        NSString* request_group_id) {
+  if (!request_group_id)
+    return base_user_agent;
   // TODO(blundell): Develop a long-term solution to this problem.
   // crbug.com/329243
   DCHECK([request_group_id length] >= kMinimumIDLength);