Make various string_util functions take StringPieces instead of char[].

chrome/browser/autocomplete/autocomplete_input.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 "chrome/browser/autocomplete/autocomplete_input.h"
 
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/external_protocol/external_protocol_handler.h"
 #include "chrome/browser/profiles/profile_io_data.h"
@@ skipping 115 matching lines @@
 AutocompleteInput::Type AutocompleteInput::Parse(
     const base::string16& text,
     const base::string16& desired_tld,
     url::Parsed* parts,
     base::string16* scheme,
     GURL* canonicalized_url) {
   size_t first_non_white = text.find_first_not_of(base::kWhitespaceUTF16, 0);
   if (first_non_white == base::string16::npos)
     return INVALID;  // All whitespace.
 
-  if (text.at(first_non_white) == L'?') {
+  if (text[first_non_white] == L'?') {
     // If the first non-whitespace character is a '?', we magically treat this
     // as a query.
     return FORCED_QUERY;
   }
 
   // Ask our parsing back-end to help us understand what the user typed.  We
   // use the URLFixerUpper here because we want to be smart about what we
   // consider a scheme.  For example, we shouldn't consider www.google.com:80
   // to have a scheme.
   url::Parsed local_parts;
@@ skipping 378 matching lines @@
   current_page_classification_ = AutocompleteInput::INVALID_SPEC;
   type_ = INVALID;
   parts_ = url::Parsed();
   scheme_.clear();
   canonicalized_url_ = GURL();
   prevent_inline_autocomplete_ = false;
   prefer_keyword_ = false;
   allow_exact_keyword_match_ = false;
   want_asynchronous_matches_ = true;
 }