Component updater must enforce that the brand length is 4.

components/update_client/utils.h

Index: components/update_client/utils.h
diff --git a/components/update_client/utils.h b/components/update_client/utils.h
index eed5bb054e9b334b23ae0c930f8066b4d8161ea4..ce0efeaaad9c95b4f5930c2361d396eb912080a6 100644
--- a/components/update_client/utils.h
+++ b/components/update_client/utils.h
@@ -96,7 +96,7 @@ std::string GetCrxComponentID(const CrxComponent& component);
 bool VerifyFileHash256(const base::FilePath& filepath,
                        const std::string& expected_hash);
 
-// Returns true if the |brand| parameter matches ^([a-zA-Z]{4})?$ .
+// Returns true if the |brand| parameter matches ^[a-zA-Z]{4}?$ .
 bool IsValidBrand(const std::string& brand);
 
 // Returns true if the |ap| parameter matches ^[-+_=a-zA-Z0-9]{0,256}$ .