Remove redundant code lines

Bug: None
Test: Non-functional change

Change-Id: I3035381a625e4c174b64cbdcf1888984fd10b454
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5169545
Reviewed-by: Roland Bock <rbock@google.com>
Commit-Queue: qian zhuoyu <zhuoyuqian@microsoft.com>
Reviewed-by: Artem Sumaneev <asumaneev@google.com>
Cr-Commit-Position: refs/heads/main@{#1243842}

components/invalidation/public/invalidation_service.h

@@ -100,8 +100,4 @@ class InvalidationService {
 
 }  // namespace invalidation
 
-namespace base {
-
-}  // namespace base
-
 #endif  // COMPONENTS_INVALIDATION_PUBLIC_INVALIDATION_SERVICE_H_