Don't use letters in me2mom access code.

remoting/host/support_access_verifier.cc

 // Copyright (c) 2011 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 "remoting/host/support_access_verifier.h"
 
 #include <stdlib.h>
 #include <vector>
 
 #include "base/logging.h"
 #include "base/rand_util.h"
 #include "base/string_util.h"
 #include "remoting/host/host_config.h"
 #include "remoting/protocol/auth_token_utils.h"
 
 namespace remoting {
 
 namespace {
-// 5 characters long from 34-letter alphabet gives 4.5M possible
+// 8 characters long from 10-letter alphabet gives 100M possible
 // host secrets with uniform distribution, which should be enough
 // for short-term passwords.
-const int kHostSecretLength = 5;
-
-// The following set includes 10 digits and Latin alphabet except I
-// and O. I and O are not used to avoid confusion with 1 and 0.
-const char kHostSecretAlphabet[] = "ABCDEFGHJKLMNPQRSTUVWXYZ0123456789";
+const int kHostSecretLength = 8;
+const char kHostSecretAlphabet[] = "0123456789";
 
 // Generates cryptographically strong random number in the range [0, max).
 int CryptoRandomInt(int max) {
   uint32 random_int32;
   base::RandBytes(&random_int32, sizeof(random_int32));
   return random_int32 % max;
 }
 
 std::string GenerateRandomHostSecret() {
   std::vector<char> result;
@@ skipping 33 matching lines @@
 void SupportAccessVerifier::OnMe2MomHostRegistered(
     bool successful, const std::string& support_id) {
   if (successful) {
     support_id_ = support_id;
   } else {
     LOG(ERROR) << "Failed to register support host";
   }
 }
 
 }  // namespace remoting