Update url_canon_icu prevent crash with GoogleUrl.

url/url_canon_icu.cc

 // Copyright 2013 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.
 
 // ICU integration functions.
 
 #include <stdlib.h>
 #include <string.h>
 
 #include "base/lazy_instance.h"
@@ skipping 145 matching lines @@
 // On error, this will return false. The output in this case is undefined.
 // TODO(jungshik): use UTF-8/ASCII version of nameToASCII.
 // Change the function signature and callers accordingly to avoid unnecessary
 // conversions in our code. In addition, consider using icu::IDNA's UTF-8/ASCII
 // version with StringByteSink. That way, we can avoid C wrappers and additional
 // string conversion.
 bool IDNToASCII(const base::char16* src, int src_len, CanonOutputW* output) {
   DCHECK(output->length() == 0);  // Output buffer is assumed empty.
 
   UIDNA* uidna = g_uidna.Get().value;
-  DCHECK(uidna != NULL);
+  if (uidna == NULL) {
+    return false;  // Prevent null-deref in uidna_nameToASCII.
+  }

[jungshik at Google, 2015/03/27 21:59:16]

This should not happen. If it happens, we have to track down the root cause. 
g_uidna is obtained here and I wonder why uidna_openUTS46 is failing. Is it
failing in Chrome? Moreover, it cannot depend on the input url.  

struct UIDNAWrapper {
  UIDNAWrapper() {
    UErrorCode err = U_ZERO_ERROR;
    // TODO(jungshik): Change options as different parties (browsers,
    // registrars, search engines) converge toward a consensus.
    value = uidna_openUTS46(UIDNA_CHECK_BIDI, &err);
    if (U_FAILURE(err))
      value = NULL;
  }

  UIDNA* value;
};

   while (true) {
     UErrorCode err = U_ZERO_ERROR;
     UIDNAInfo info = UIDNA_INFO_INITIALIZER;
     int output_length = uidna_nameToASCII(uidna, src, src_len, output->data(),
                                           output->capacity(), &info, &err);
     if (U_SUCCESS(err) && info.errors == 0) {
       output->set_length(output_length);
       return true;
     }
 
     // TODO(jungshik): Look at info.errors to handle them case-by-case basis
     // if necessary.
     if (err != U_BUFFER_OVERFLOW_ERROR || info.errors != 0)
       return false;  // Unknown error, give up.
 
     // Not enough room in our buffer, expand.
     output->Resize(output_length);
   }
 }
 
 }  // namespace url