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

chrome/browser/autocomplete/builtin_provider.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/builtin_provider.h"
 
 #include <algorithm>
 
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 89 matching lines @@
              base::string16(), styles);
   } else {
     // Match input about: or chrome: URL input against builtin chrome URLs.
     GURL url = URLFixerUpper::FixupURL(base::UTF16ToUTF8(text), std::string());
     // BuiltinProvider doesn't know how to suggest valid ?query or #fragment
     // extensions to chrome: URLs.
     if (url.SchemeIs(content::kChromeUIScheme) && url.has_host() &&
         !url.has_query() && !url.has_ref()) {
       // Include the path for sub-pages (e.g. "chrome://settings/browser").
       base::string16 host_and_path = base::UTF8ToUTF16(url.host() + url.path());
-      base::TrimString(host_and_path, base::ASCIIToUTF16("/").c_str(),
-                       &host_and_path);
+      base::TrimString(host_and_path, base::ASCIIToUTF16("/"), &host_and_path);
       size_t match_length = kChrome.length() + host_and_path.length();
       for (Builtins::const_iterator i(builtins_.begin());
           (i != builtins_.end()) && (matches_.size() < kMaxMatches); ++i) {
         if (StartsWith(*i, host_and_path, false)) {
           ACMatchClassifications styles;
           // Highlight the "chrome://" scheme, even for input "about:foo".
           styles.push_back(ACMatchClassification(0, kMatch));
           base::string16 match_string = kChrome + *i;
           if (match_string.length() > match_length)
             styles.push_back(ACMatchClassification(match_length, kUrl));
@@ skipping 22 matching lines @@
                                const ACMatchClassifications& styles) {
   AutocompleteMatch match(this, kRelevance, false,
                           AutocompleteMatchType::NAVSUGGEST);
   match.fill_into_edit = match_string;
   match.inline_autocompletion = inline_completion;
   match.destination_url = GURL(match_string);
   match.contents = match_string;
   match.contents_class = styles;
   matches_.push_back(match);
 }