Remove |using base::StringPiece| from net/spdy header files.

net/spdy/spdy_alt_svc_wire_format.cc

 // Copyright (c) 2015 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 "net/spdy/spdy_alt_svc_wire_format.h"
 
 #include <limits>
 #include <string>
 
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 
 namespace net {
 
+using base::StringPiece;
+
 namespace {
 
 template <class T>
 bool ParsePositiveIntegerImpl(StringPiece::const_iterator c,
                               StringPiece::const_iterator end,
                               T* value) {
   *value = 0;
   for (; c != end && isdigit(*c); ++c) {
     if (*value > std::numeric_limits<T>::max() / 10) {
       return false;
@@ skipping 359 matching lines @@
   ++c;
   double place_value = 0.1;
   for (; c != end && isdigit(*c); ++c) {
     *probability += place_value * (*c - '0');
     place_value *= 0.1;
   }
   return (c == end && *probability <= 1.0);
 }
 
 }  // namespace net