[AiS] Make base64 encoding URL-safe.

chrome/browser/autocomplete/search_provider.cc

Index: chrome/browser/autocomplete/search_provider.cc
diff --git a/chrome/browser/autocomplete/search_provider.cc b/chrome/browser/autocomplete/search_provider.cc
index a06fac50988e8643326f8bad50c7402505eefe0f..7a42af1e6ad975664bdff790f41e0d74f7c5a589 100644
--- a/chrome/browser/autocomplete/search_provider.cc
+++ b/chrome/browser/autocomplete/search_provider.cc
@@ -1152,6 +1152,10 @@ std::string SearchProvider::GetSessionToken() {
     std::string raw_data;
     base::RandBytes(WriteInto(&raw_data, kTokenBytes + 1), kTokenBytes);
     base::Base64Encode(raw_data, &current_token_);
+
+    // Make the base64 encoded value URL and filename safe(see RFC 3548).
+    std::replace(current_token_.begin(), current_token_.end(), '+', '-');
+    std::replace(current_token_.begin(), current_token_.end(), '/', '_');
   }
 
   // Extend expiration time another 60 seconds.