Delete old client info migration behavior.

components/metrics/metrics_state_manager.cc

Index: components/metrics/metrics_state_manager.cc
diff --git a/components/metrics/metrics_state_manager.cc b/components/metrics/metrics_state_manager.cc
index 4cae20d3ae7be6df2815d0367e2e16d5998d86ba..83d62b5f4f8bb701d04dda2d9fce792bb462494c 100644
--- a/components/metrics/metrics_state_manager.cc
+++ b/components/metrics/metrics_state_manager.cc
@@ -92,16 +92,10 @@ void MetricsStateManager::ForceClientIdCreation() {
     client_id_.swap(client_id_from_prefs);
   }
 
-  if (!client_id_.empty()) {
-    // It is technically sufficient to only save a backup of the client id when
-    // it is initially generated below, but since the backup was only introduced
-    // in M38, seed it explicitly from here for some time.
-    BackUpCurrentClientInfo();
+  if (!client_id_.empty())
     return;
-  }
 
-  const std::unique_ptr<ClientInfo> client_info_backup =
-      LoadClientInfoAndMaybeMigrate();
+  const std::unique_ptr<ClientInfo> client_info_backup = LoadClientInfo();
   if (client_info_backup) {
     client_id_ = client_info_backup->client_id;
 
@@ -233,36 +227,12 @@ void MetricsStateManager::BackUpCurrentClientInfo() {
   store_client_info_.Run(client_info);
 }
 
-std::unique_ptr<ClientInfo>
-MetricsStateManager::LoadClientInfoAndMaybeMigrate() {
+std::unique_ptr<ClientInfo> MetricsStateManager::LoadClientInfo() {
   std::unique_ptr<ClientInfo> client_info = load_client_info_.Run();
 
-  // Prior to 2014-07, the client ID was stripped of its dashes before being
-  // saved. Migrate back to a proper GUID if this is the case. This migration
-  // code can be removed in M41+.
-  const size_t kGUIDLengthWithoutDashes = 32U;
-  if (client_info &&
-      client_info->client_id.length() == kGUIDLengthWithoutDashes) {
-    DCHECK(client_info->client_id.find('-') == std::string::npos);
-
-    std::string client_id_with_dashes;
-    client_id_with_dashes.reserve(kGUIDLengthWithoutDashes + 4U);
-    std::string::const_iterator client_id_it = client_info->client_id.begin();
-    for (size_t i = 0; i < kGUIDLengthWithoutDashes + 4U; ++i) {
-      if (i == 8U || i == 13U || i == 18U || i == 23U) {
-        client_id_with_dashes.push_back('-');
-      } else {
-        client_id_with_dashes.push_back(*client_id_it);
-        ++client_id_it;
-      }
-    }
-    DCHECK(client_id_it == client_info->client_id.end());
-    client_info->client_id.assign(client_id_with_dashes);
-  }
-
-  // The GUID retrieved (and possibly fixed above) should be valid unless
-  // retrieval failed. If not, return nullptr. This will result in a new GUID
-  // being generated by the calling function ForceClientIdCreation().
+  // The GUID retrieved should be valid unless retrieval failed.
+  // If not, return nullptr. This will result in a new GUID being generated by
+  // the calling function ForceClientIdCreation().
   if (client_info && !base::IsValidGUID(client_info->client_id))
     return nullptr;