crypto: Remove forbidden using namespace directive.

crypto/p224_unittest.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 <string.h>
 #include <stdio.h>
 
 #include "crypto/p224.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 
-using namespace crypto;
+namespace crypto {
+
 using p224::Point;
 
 // kBasePointExternal is the P224 base point in external representation.
 static const uint8 kBasePointExternal[56] = {
   0xb7, 0x0e, 0x0c, 0xbd, 0x6b, 0xb4, 0xbf, 0x7f,
   0x32, 0x13, 0x90, 0xb9, 0x4a, 0x03, 0xc1, 0xd3,
   0x56, 0xc2, 0x11, 0x22, 0x34, 0x32, 0x80, 0xd6,
   0x11, 0x5c, 0x1d, 0x21, 0xbd, 0x37, 0x63, 0x88,
   0xb5, 0xf7, 0x23, 0xfb, 0x4c, 0x22, 0xdf, 0xe6,
   0xcd, 0x43, 0x75, 0xa0, 0x5a, 0x07, 0x47, 0x64,
@@ skipping 789 matching lines @@
   memset(zeros, 0, sizeof(zeros));
 
   // Test that x^0 = ∞.
   Point a;
   p224::ScalarBaseMult(reinterpret_cast<const uint8*>(zeros), &a);
   EXPECT_TRUE(memcmp(zeros, a.ToString().data(), sizeof(zeros)) == 0);
 
   // We shouldn't allow ∞ to be imported.
   EXPECT_FALSE(a.SetFromString(std::string(zeros, sizeof(zeros))));
 }
+
+}  // namespace crypto