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

chrome/browser/drive/drive_api_util.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/drive/drive_api_util.h"
 
 #include <string>
 
 #include "base/files/file.h"
 #include "base/logging.h"
@@ skipping 48 matching lines @@
     }
     result.push_back(str[i]);
   }
   return result;
 }
 
 std::string TranslateQuery(const std::string& original_query) {
   // In order to handle non-ascii white spaces correctly, convert to UTF16.
   base::string16 query = base::UTF8ToUTF16(original_query);
   const base::string16 kDelimiter(
-      base::kWhitespaceUTF16 +
-      base::string16(1, static_cast<base::char16>('"')));
+      base::kWhitespaceUTF16 + base::ASCIIToUTF16("\""));
 
   std::string result;
   for (size_t index = query.find_first_not_of(base::kWhitespaceUTF16);
        index != base::string16::npos;
        index = query.find_first_not_of(base::kWhitespaceUTF16, index)) {
     bool is_exclusion = (query[index] == '-');
     if (is_exclusion)
       ++index;
     if (index == query.length()) {
       // Here, the token is '-' and it should be ignored.
@@ skipping 350 matching lines @@
 
   base::MD5Digest digest;
   base::MD5Final(&digest, &context);
   return MD5DigestToBase16(digest);
 }
 
 const char kWapiRootDirectoryResourceId[] = "folder:root";
 
 }  // namespace util
 }  // namespace drive