Avoid loading an empty token when decrypt failed

components/signin/core/browser/webdata/token_service_table.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/signin/core/browser/webdata/token_service_table.h"
 
 #include <map>
 #include <string>
 
 #include "base/logging.h"
+#include "base/metrics/user_metrics.h"
 #include "components/os_crypt/os_crypt.h"
 #include "components/webdata/common/web_database.h"
 #include "sql/statement.h"
 
 namespace {
 
 WebDatabaseTable::TypeKey GetKey() {
   // We just need a unique constant. Use the address of a static that
   // COMDAT folding won't touch in an optimizing linker.
   static int table_key = 0;
@@ skipping 65 matching lines @@
              static_cast<int>(encrypted_token.length()));
 
   return s.Run();
 }
 
 bool TokenServiceTable::GetAllTokens(
     std::map<std::string, std::string>* tokens) {
   sql::Statement s(db_->GetUniqueStatement(
       "SELECT service, encrypted_token FROM token_service"));
 
-  if (!s.is_valid())
+  if (!s.is_valid()) {
+    LOG(ERROR) << "Failed to load tokens (invalid SQL statement).";
+    base::RecordAction(
+        base::UserMetricsAction("Signin_TokenTable_GetAllTokensInvalidSql"));

[Alexei Svitkine (slow), 2017/02/02 17:22:13]

These don't look like actions initiated by a user. You should use an enumerated
histogram instead.

[msarda, 2017/02/06 10:36:47]

Done.

     return false;
+  }
 
   while (s.Step()) {
     std::string encrypted_token;
     std::string decrypted_token;
     std::string service;
     service = s.ColumnString(0);
     bool entry_ok = !service.empty() &&
                     s.ColumnBlobAsString(1, &encrypted_token);
     if (entry_ok) {
-      OSCrypt::DecryptString(encrypted_token, &decrypted_token);
-      (*tokens)[service] = decrypted_token;
+      if (OSCrypt::DecryptString(encrypted_token, &decrypted_token)) {
+        (*tokens)[service] = decrypted_token;
+        base::RecordAction(
+            base::UserMetricsAction("Signin_TokenTable_LoadTokenSuccess"));
+      } else {
+        // Chrome relies on native APIs to encrypt and decrypt the tokens which
+        // may fail (see http://crbug.com/686485).
+        LOG(ERROR) << "Failed to decrypt token for service " << service;
+        base::RecordAction(
+            base::UserMetricsAction("Signin_TokenTable_DecryptFailed"));
+      }
     } else {
-      NOTREACHED();
+      LOG(ERROR) << "Bad token entry for service " << service;
+      base::RecordAction(base::UserMetricsAction("Signin_TokenTable_BadEntry"));
       return false;
     }
   }
   return true;
 }