Return if a host name in an URLPattern has no non-whitespace characters.

extensions/common/url_pattern.cc

 // Copyright (c) 2012 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 "extensions/common/url_pattern.h"
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
@@ skipping 201 matching lines @@
       return PARSE_ERROR_EMPTY_HOST;
 
     if (host_end_pos == std::string::npos)
       return PARSE_ERROR_EMPTY_PATH;
 
     host_ = pattern.substr(host_start_pos, host_end_pos - host_start_pos);
 
     // The first component can optionally be '*' to match all subdomains.
     std::vector<std::string> host_components;
     base::SplitString(host_, '.', &host_components);
+
+    // Could be empty if the host only consists of whitespace characters.
+    if (host_components.empty())
+      return PARSE_ERROR_EMPTY_HOST;
+
     if (host_components[0] == "*") {
       match_subdomains_ = true;
       host_components.erase(host_components.begin(),
                             host_components.begin() + 1);
     }
     host_ = JoinString(host_components, '.');
 
     path_start_pos = host_end_pos;
   }
 
@@ skipping 304 matching lines @@
   }
 
   return result;
 }
 
 // static
 const char* URLPattern::GetParseResultString(
     URLPattern::ParseResult parse_result) {
   return kParseResultMessages[parse_result];
 }