Fix build issues in base/ for Android x64

base/json/json_writer.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 "base/json/json_writer.h"
 
 #include <cmath>
 
 #include "base/json/string_escape.h"
 #include "base/logging.h"
@@ skipping 78 matching lines @@
       // makes sure that when we read the JSON back, it's interpreted as a
       // real rather than an int.
       if (real.find('.') == std::string::npos &&
           real.find('e') == std::string::npos &&
           real.find('E') == std::string::npos) {
         real.append(".0");
       }
       // The JSON spec requires that non-integer values in the range (-1,1)
       // have a zero before the decimal point - ".52" is not valid, "0.52" is.
       if (real[0] == '.') {
-        real.insert(0U, 1U, '0');
+        real.insert(static_cast<size_t>(0), static_cast<size_t>(1), '0');
       } else if (real.length() > 1 && real[0] == '-' && real[1] == '.') {
         // "-.1" bad "-0.1" good
-        real.insert(1U, 1U, '0');
+        real.insert(static_cast<size_t>(1), static_cast<size_t>(1), '0');
       }
       json_string_->append(real);
       return result;
     }
 
     case Value::TYPE_STRING: {
       std::string value;
       bool result = node->GetAsString(&value);
       DCHECK(result);
       EscapeJSONString(value, true, json_string_);
@@ skipping 85 matching lines @@
   }
   NOTREACHED();
   return false;
 }
 
 void JSONWriter::IndentLine(size_t depth) {
   json_string_->append(depth * 3U, ' ');
 }
 
 }  // namespace base